diff --git a/README.md b/README.md
index 400b4c0..049050c 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,7 @@ bundle exec rspec
 Leader/follower tournament sync docs:
 
 - [doc/leader_follower.md](doc/leader_follower.md)
+- [doc/timer_api.md](doc/timer_api.md)
 - [doc/beamer_live_updates.md](doc/beamer_live_updates.md)
 
 ## Docker
diff --git a/app/channels/tournament_timers_channel.rb b/app/channels/tournament_timers_channel.rb
new file mode 100644
index 0000000..b630d13
--- /dev/null
+++ b/app/channels/tournament_timers_channel.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class TournamentTimersChannel < ApplicationCable::Channel
+  def subscribed
+    tournament = Tournament.find(params[:tournament_id])
+    stream_for tournament
+    transmit TournamentTimerBroadcastPayload.build(tournament)
+  end
+end
diff --git a/app/controllers/tournaments_controller.rb b/app/controllers/tournaments_controller.rb
index c64e8a4..5fe10f0 100644
--- a/app/controllers/tournaments_controller.rb
+++ b/app/controllers/tournaments_controller.rb
@@ -12,15 +12,15 @@ class TournamentsController < ApplicationController
   end
 
   before_action :set_tournament_for_show, only: %i[show]
-  before_action :set_tournament, only: %i[update destroy set_timer_end timer_end sync_state test_sync]
-  before_action :authenticate_user!, only: %i[create update destroy set_timer_end test_sync]
-  before_action -> { require_owner! @tournament.owner }, only: %i[update destroy set_timer_end test_sync]
+  before_action :set_tournament, only: %i[update destroy set_timer timer sync_state test_sync]
+  before_action :authenticate_user!, only: %i[create update destroy set_timer test_sync]
+  before_action -> { require_owner! @tournament.owner }, only: %i[update destroy set_timer test_sync]
   before_action :validate_create_params, only: %i[create]
   before_action :validate_update_params, only: %i[update]
-  before_action :validate_set_timer_end_params, only: %i[set_timer_end]
+  before_action :validate_set_timer_params, only: %i[set_timer]
   before_action :ensure_update_allowed!, only: %i[update]
   before_action :ensure_destroy_allowed!, only: %i[destroy]
-  before_action :ensure_timer_update_allowed!, only: %i[set_timer_end]
+  before_action :ensure_timer_update_allowed!, only: %i[set_timer]
   before_action :authorize_sync_request!, only: %i[sync_state]
   rescue_from ActiveRecord::RecordNotFound, with: :render_not_found_error
 
@@ -129,14 +129,14 @@ class TournamentsController < ApplicationController
     @tournament.destroy
   end
 
-  # GET /tournaments/:id/timer_end
-  def timer_end
-    render json: { timer_end: serialize_timer_end(@tournament.timer_end) }
+  # GET /tournaments/:id/timer
+  def timer
+    render json: serialize_timer_state(@tournament)
   end
 
-  # PATCH /tournaments/:id/set_timer_end
-  def set_timer_end
-    if @tournament.update(timer_end_params)
+  # PATCH /tournaments/:id/timer
+  def set_timer
+    if @tournament.update(timer_params)
       push_sync_if_needed!(@tournament)
       render json: @tournament
     else
@@ -171,12 +171,18 @@ class TournamentsController < ApplicationController
 
   private
 
-  def timer_end_params
-    { timer_end: params[:timer_end] }
+  def timer_params
+    {
+      timestamp: params[:timestamp],
+      timer_mode: params[:timer_mode]
+    }
   end
 
-  def serialize_timer_end(timer_end)
-    timer_end&.iso8601
+  def serialize_timer_state(tournament)
+    {
+      timestamp: tournament.timestamp&.iso8601,
+      timer_mode: tournament.timer_mode
+    }
   end
 
   def organize_teams_in_groups(teams)
@@ -326,41 +332,70 @@ class TournamentsController < ApplicationController
     TournamentSyncEnqueue.call(tournament)
   end
 
-  def validate_set_timer_end_params
-    timer_end = params[:timer_end]
-    timer_end_seconds = params[:timer_end_seconds]
+  def validate_set_timer_params
+    timestamp = params[:timestamp]
+    timestamp_seconds = params[:timestamp_seconds]
+    timer_mode = params[:timer_mode]
+    clear_timer = ActiveModel::Type::Boolean.new.cast(params[:clear_timer])
 
-    # throw error if both timer_end and timer_end_seconds are present
-    if timer_end.present? && timer_end_seconds.present?
-      return render json: { error: 'Only one of timer_end or timer_end_seconds is allowed' }, status: :unprocessable_entity
+    if clear_timer
+      if timestamp.present? || timestamp_seconds.present? || timer_mode.present?
+        return render json: { error: 'clear_timer cannot be combined with timestamp values or timer_mode' },
+                      status: :unprocessable_entity
+      end
+
+      params[:timestamp] = nil
+      params[:timer_mode] = nil
+      return
     end
 
-    if timer_end_seconds.present?
+    if timer_mode.present? && !%w[countdown countup].include?(timer_mode)
+      return render json: { error: 'Invalid timer_mode' }, status: :unprocessable_entity
+    end
+
+    # throw error if both timestamp and timestamp_seconds are present
+    if timestamp.present? && timestamp_seconds.present?
+      return render json: { error: 'Only one of timestamp or timestamp_seconds is allowed' }, status: :unprocessable_entity
+    end
+
+    if timer_mode == 'countup' && timestamp_seconds.present?
+      return render json: { error: 'timestamp_seconds is only allowed for countdown mode' }, status: :unprocessable_entity
+    end
+
+    if timestamp_seconds.present?
       begin
-        timer_end_seconds = Integer(timer_end_seconds)
+        timestamp_seconds = Integer(timestamp_seconds)
       rescue ArgumentError
         return render json: { error: 'Invalid seconds format' }, status: :unprocessable_entity
       end
 
-      return render json: { error: 'Timer end must be in the future' }, status: :unprocessable_entity if timer_end_seconds <= 0
+      return render json: { error: 'Timestamp must be in the future for countdown mode' }, status: :unprocessable_entity if timestamp_seconds <= 0
 
-      parsed_time = Time.zone.now + timer_end_seconds
-      params[:timer_end] = parsed_time
-    elsif timer_end.present?
+      parsed_time = Time.zone.now + timestamp_seconds
+      params[:timestamp] = parsed_time
+      params[:timer_mode] = 'countdown'
+    elsif timestamp.present?
       begin
-        parsed_time = Time.zone.parse(timer_end)
+        parsed_time = Time.zone.parse(timestamp)
         if parsed_time.nil?
-          return render json: { error: 'Invalid datetime format' }, status: :unprocessable_entity
-        elsif !parsed_time.future?
-          return render json: { error: 'Timer end must be in the future' }, status: :unprocessable_entity
+          return render json: { error: 'Invalid timestamp format' }, status: :unprocessable_entity
+        elsif timer_mode != 'countup' && !parsed_time.future?
+          return render json: { error: 'Timestamp must be in the future for countdown mode' }, status: :unprocessable_entity
         end
 
-        params[:timer_end] = parsed_time
+        params[:timestamp] = parsed_time
+        params[:timer_mode] = timer_mode.presence || 'countdown'
       rescue ArgumentError
-        return render json: { error: 'Invalid datetime format' }, status: :unprocessable_entity
+        return render json: { error: 'Invalid timestamp format' }, status: :unprocessable_entity
       end
+    elsif timer_mode == 'countup'
+      params[:timestamp] = Time.zone.now
+    elsif timer_mode.present?
+      return render json: { error: 'timer_mode requires timestamp, timestamp_seconds, or clear_timer' },
+                    status: :unprocessable_entity
     else
-      return render json: { error: 'Timer end is required' }, status: :unprocessable_entity
+      return render json: { error: 'timestamp, timestamp_seconds, or clear_timer is required' },
+                    status: :unprocessable_entity
     end
   end
 end
diff --git a/app/models/tournament.rb b/app/models/tournament.rb
index 729fdab..65c22d0 100644
--- a/app/models/tournament.rb
+++ b/app/models/tournament.rb
@@ -11,6 +11,7 @@ class Tournament < ApplicationRecord
 
   validates :name, presence: true
   validates :code, presence: true, uniqueness: true
+  validates :timer_mode, inclusion: { in: %w[countdown countup] }, allow_nil: true
   validates :sync_target_url, format: URI::DEFAULT_PARSER.make_regexp(%w[http https]), allow_blank: true
   validate :sync_configuration_is_complete
 
@@ -21,6 +22,7 @@ class Tournament < ApplicationRecord
   after_initialize :generate_code
   after_create_commit :ensure_default_beamer!
   before_validation :clear_follower_sync_token_when_disabling_read_only_mode
+  after_commit :broadcast_timer_state_change, if: :saved_change_to_timer_state?
 
   def matches
     [stages.map(&:matches), stages.map { |s| s.groups.map(&:matches) }].flatten
@@ -92,4 +94,12 @@ class Tournament < ApplicationRecord
 
     self.sync_auth_token = nil
   end
+
+  def saved_change_to_timer_state?
+    saved_change_to_timestamp? || saved_change_to_timer_mode?
+  end
+
+  def broadcast_timer_state_change
+    TournamentTimerBroadcast.call(id)
+  end
 end
diff --git a/app/serializers/tournament_serializer.rb b/app/serializers/tournament_serializer.rb
index 9389365..46009a1 100644
--- a/app/serializers/tournament_serializer.rb
+++ b/app/serializers/tournament_serializer.rb
@@ -11,10 +11,12 @@ class TournamentSerializer < SimpleTournamentSerializer
   has_many :stages
   has_many :team_action_lists
 
-  attribute :timer_end do
-    object.timer_end&.iso8601
+  attribute :timestamp do
+    object.timestamp&.iso8601
   end
 
+  attribute :timer_mode
+
   attribute :sync_last_pushed_at, if: :sync_metadata_visible? do
     object.sync_last_pushed_at&.iso8601
   end
diff --git a/app/services/tournament_snapshot_builder.rb b/app/services/tournament_snapshot_builder.rb
index 48b61d4..8ca4a26 100644
--- a/app/services/tournament_snapshot_builder.rb
+++ b/app/services/tournament_snapshot_builder.rb
@@ -22,7 +22,8 @@ class TournamentSnapshotBuilder
 
   def build
     payload = tournament.attributes.symbolize_keys.slice(*ROOT_ATTRIBUTES)
-    payload[:timer_end] = tournament.timer_end&.iso8601
+    payload[:timestamp] = tournament.timestamp&.iso8601
+    payload[:timer_mode] = tournament.timer_mode
     payload[:sync_generated_at] = Time.current.iso8601(6)
     payload[:teams] = teams_payload
     payload[:beamers] = beamers_payload
diff --git a/app/services/tournament_snapshot_importer.rb b/app/services/tournament_snapshot_importer.rb
index 0a1657f..d03beba 100644
--- a/app/services/tournament_snapshot_importer.rb
+++ b/app/services/tournament_snapshot_importer.rb
@@ -67,7 +67,8 @@ class TournamentSnapshotImporter
   def update_tournament!
     root_attrs = snapshot.slice(*ROOT_ATTRIBUTES)
     root_attrs[:code] = tournament.code if code_taken_by_another_tournament?(root_attrs[:code])
-    root_attrs[:timer_end] = parse_time(snapshot[:timer_end])
+    root_attrs[:timestamp] = parse_time(snapshot[:timestamp])
+    root_attrs[:timer_mode] = snapshot[:timer_mode]
     root_attrs[:sync_source_tournament_id] = snapshot[:id]
     root_attrs[:sync_last_imported_snapshot_at] = snapshot_generated_at
     tournament.update!(root_attrs)
diff --git a/app/services/tournament_sync_schema.rb b/app/services/tournament_sync_schema.rb
index d31f49f..3d85a2d 100644
--- a/app/services/tournament_sync_schema.rb
+++ b/app/services/tournament_sync_schema.rb
@@ -12,7 +12,8 @@ class TournamentSyncSchema
         playoff_teams_amount
         instant_finalists_amount
         intermediate_round_participants_amount
-        timer_end
+        timestamp
+        timer_mode
       ].freeze,
       ignored: %w[
         user_id
diff --git a/app/services/tournament_timer_broadcast.rb b/app/services/tournament_timer_broadcast.rb
new file mode 100644
index 0000000..9d8e198
--- /dev/null
+++ b/app/services/tournament_timer_broadcast.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class TournamentTimerBroadcast
+  class << self
+    def call(tournament_id)
+      tournament = Tournament.find_by(id: tournament_id)
+      return if tournament.nil?
+
+      TournamentTimersChannel.broadcast_to(
+        tournament,
+        TournamentTimerBroadcastPayload.build(tournament)
+      )
+    end
+  end
+end
diff --git a/app/services/tournament_timer_broadcast_payload.rb b/app/services/tournament_timer_broadcast_payload.rb
new file mode 100644
index 0000000..9b790de
--- /dev/null
+++ b/app/services/tournament_timer_broadcast_payload.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class TournamentTimerBroadcastPayload
+  class << self
+    def build(tournament)
+      {
+        type: 'timer.updated',
+        tournament_id: tournament.id,
+        timestamp: tournament.timestamp&.iso8601,
+        timer_mode: tournament.timer_mode
+      }
+    end
+  end
+end
diff --git a/config/routes.rb b/config/routes.rb
index 9c53ca4..7ef1030 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -31,8 +31,8 @@ Rails.application.routes.draw do
       end
     end
     member do
-      get :timer_end
-      patch :set_timer_end
+      get :timer
+      patch :timer, action: :set_timer
       patch :sync_state
       post :test_sync
     end
diff --git a/db/migrate/20260423133000_add_timer_mode_to_tournaments.rb b/db/migrate/20260423133000_add_timer_mode_to_tournaments.rb
new file mode 100644
index 0000000..07f5ef2
--- /dev/null
+++ b/db/migrate/20260423133000_add_timer_mode_to_tournaments.rb
@@ -0,0 +1,5 @@
+class AddTimerModeToTournaments < ActiveRecord::Migration[7.0]
+  def change
+    add_column :tournaments, :timer_mode, :string
+  end
+end
diff --git a/db/migrate/20260424120000_rename_timer_end_to_timestamp_on_tournaments.rb b/db/migrate/20260424120000_rename_timer_end_to_timestamp_on_tournaments.rb
new file mode 100644
index 0000000..d02680c
--- /dev/null
+++ b/db/migrate/20260424120000_rename_timer_end_to_timestamp_on_tournaments.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class RenameTimerEndToTimestampOnTournaments < ActiveRecord::Migration[7.0]
+  def change
+    rename_column :tournaments, :timer_end, :timestamp
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
new file mode 100644
index 0000000..656b26b
--- /dev/null
+++ b/db/schema.rb
@@ -0,0 +1,223 @@
+# This file is auto-generated from the current state of the database. Instead
+# of editing this file, please use the migrations feature of Active Record to
+# incrementally modify your database, and then regenerate this schema definition.
+#
+# This file is the source Rails uses to define your schema when running `bin/rails
+# db:schema:load`. When creating a new database, `bin/rails db:schema:load` tends to
+# be faster and is potentially less error prone than running all of your
+# migrations from scratch. Old migrations may fail to apply correctly if those
+# migrations use external dependencies or application code.
+#
+# It's strongly recommended that you check this file into your version control system.
+
+ActiveRecord::Schema[7.0].define(version: 2026_04_24_120000) do
+  create_table "beamers", force: :cascade do |t|
+    t.string "name", null: false
+    t.string "display_state", default: "matches_all", null: false
+    t.boolean "is_default", default: false
+    t.string "qr_code_url"
+    t.string "logo_url"
+    t.integer "tournament_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.integer "sync_source_id"
+    t.index ["tournament_id", "name"], name: "index_beamers_on_tournament_id_and_name", unique: true
+    t.index ["tournament_id"], name: "index_beamers_on_tournament_id"
+  end
+
+  create_table "bets", force: :cascade do |t|
+    t.integer "user_id", null: false
+    t.integer "match_id", null: false
+    t.integer "team_id"
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
+    t.index ["match_id"], name: "index_bets_on_match_id"
+    t.index ["team_id"], name: "index_bets_on_team_id"
+    t.index ["user_id"], name: "index_bets_on_user_id"
+  end
+
+  create_table "group_scores", force: :cascade do |t|
+    t.integer "group_points", default: 0
+    t.integer "scored_points", default: 0
+    t.integer "received_points", default: 0
+    t.integer "team_id", null: false
+    t.integer "group_id", null: false
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
+    t.integer "position", default: 0
+    t.integer "sync_source_id"
+    t.index ["group_id"], name: "index_group_scores_on_group_id"
+    t.index ["team_id"], name: "index_group_scores_on_team_id"
+  end
+
+  create_table "groups", force: :cascade do |t|
+    t.integer "number"
+    t.integer "stage_id", null: false
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
+    t.integer "sync_source_id"
+    t.index ["stage_id"], name: "index_groups_on_stage_id"
+  end
+
+  create_table "match_scores", force: :cascade do |t|
+    t.integer "points", default: 0
+    t.integer "match_id", null: false
+    t.integer "team_id", null: false
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
+    t.integer "hidden_points", default: 0, null: false
+    t.integer "sync_source_id"
+    t.index ["match_id"], name: "index_match_scores_on_match_id"
+    t.index ["team_id"], name: "index_match_scores_on_team_id"
+  end
+
+  create_table "matches", force: :cascade do |t|
+    t.integer "state", default: 0
+    t.integer "position"
+    t.integer "stage_id"
+    t.integer "group_id"
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
+    t.boolean "decider", default: false, null: false
+    t.integer "sync_source_id"
+    t.index ["group_id"], name: "index_matches_on_group_id"
+    t.index ["stage_id"], name: "index_matches_on_stage_id"
+  end
+
+  create_table "stages", force: :cascade do |t|
+    t.integer "level"
+    t.integer "state", default: 0
+    t.integer "tournament_id", null: false
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
+    t.integer "sync_source_id"
+    t.index ["tournament_id"], name: "index_stages_on_tournament_id"
+  end
+
+  create_table "team_action_items", force: :cascade do |t|
+    t.integer "team_action_list_id", null: false
+    t.integer "team_id", null: false
+    t.boolean "completed", default: false, null: false
+    t.datetime "completed_at"
+    t.integer "sync_source_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["sync_source_id"], name: "index_team_action_items_on_sync_source_id"
+    t.index ["team_action_list_id", "team_id"], name: "index_team_action_items_on_team_action_list_id_and_team_id", unique: true
+    t.index ["team_action_list_id"], name: "index_team_action_items_on_team_action_list_id"
+    t.index ["team_id"], name: "index_team_action_items_on_team_id"
+  end
+
+  create_table "team_action_lists", force: :cascade do |t|
+    t.integer "tournament_id", null: false
+    t.string "name", null: false
+    t.string "key", null: false
+    t.string "action_name", null: false
+    t.string "source", null: false
+    t.integer "sync_source_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["sync_source_id"], name: "index_team_action_lists_on_sync_source_id"
+    t.index ["tournament_id", "key"], name: "index_team_action_lists_on_tournament_id_and_key", unique: true
+    t.index ["tournament_id"], name: "index_team_action_lists_on_tournament_id"
+  end
+
+  create_table "teams", force: :cascade do |t|
+    t.string "name"
+    t.integer "tournament_id"
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
+    t.integer "sync_source_id"
+    t.index ["tournament_id"], name: "index_teams_on_tournament_id"
+  end
+
+  create_table "tournament_sync_queue_entries", force: :cascade do |t|
+    t.integer "tournament_id", null: false
+    t.text "snapshot_json", null: false
+    t.datetime "next_attempt_at", null: false
+    t.datetime "last_attempt_at"
+    t.datetime "locked_at"
+    t.string "lock_token"
+    t.integer "attempts", default: 0, null: false
+    t.string "status", default: "pending", null: false
+    t.string "last_error"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["next_attempt_at"], name: "index_tournament_sync_queue_entries_on_next_attempt_at"
+    t.index ["status"], name: "index_tournament_sync_queue_entries_on_status"
+    t.index ["tournament_id"], name: "index_tournament_sync_queue_entries_on_tournament_id", unique: true
+  end
+
+  create_table "tournaments", force: :cascade do |t|
+    t.string "name", null: false
+    t.string "code", null: false
+    t.string "description"
+    t.boolean "public", default: true
+    t.integer "playoff_teams_amount", default: 0
+    t.integer "instant_finalists_amount", default: 0
+    t.integer "intermediate_round_participants_amount", default: 0
+    t.integer "user_id", null: false
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
+    t.datetime "timestamp"
+    t.boolean "read_only_mode", default: false, null: false
+    t.string "sync_target_url"
+    t.string "sync_auth_token"
+    t.integer "sync_source_tournament_id"
+    t.datetime "sync_last_pushed_at"
+    t.string "sync_last_push_error"
+    t.datetime "sync_last_imported_snapshot_at"
+    t.string "timer_mode"
+    t.index ["code"], name: "index_tournaments_on_code", unique: true
+    t.index ["user_id"], name: "index_tournaments_on_user_id"
+  end
+
+  create_table "users", force: :cascade do |t|
+    t.string "provider", default: "email", null: false
+    t.string "uid", default: "", null: false
+    t.string "encrypted_password", default: "", null: false
+    t.string "reset_password_token"
+    t.datetime "reset_password_sent_at", precision: nil
+    t.boolean "allow_password_change", default: false
+    t.datetime "remember_created_at", precision: nil
+    t.integer "sign_in_count", default: 0, null: false
+    t.datetime "current_sign_in_at", precision: nil
+    t.datetime "last_sign_in_at", precision: nil
+    t.string "current_sign_in_ip"
+    t.string "last_sign_in_ip"
+    t.string "confirmation_token"
+    t.datetime "confirmed_at", precision: nil
+    t.datetime "confirmation_sent_at", precision: nil
+    t.string "unconfirmed_email"
+    t.string "username"
+    t.string "email"
+    t.text "tokens"
+    t.datetime "created_at", precision: nil, null: false
+    t.datetime "updated_at", precision: nil, null: false
+    t.index ["confirmation_token"], name: "index_users_on_confirmation_token", unique: true
+    t.index ["email"], name: "index_users_on_email", unique: true
+    t.index ["provider"], name: "index_users_on_provider"
+    t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
+    t.index ["uid"], name: "index_users_on_uid", unique: true
+    t.index ["username"], name: "index_users_on_username", unique: true
+  end
+
+  add_foreign_key "beamers", "tournaments", on_delete: :cascade
+  add_foreign_key "bets", "matches", on_delete: :cascade
+  add_foreign_key "bets", "teams", on_delete: :cascade
+  add_foreign_key "bets", "users", on_delete: :cascade
+  add_foreign_key "group_scores", "groups", on_delete: :cascade
+  add_foreign_key "group_scores", "teams", on_delete: :cascade
+  add_foreign_key "groups", "stages", on_delete: :cascade
+  add_foreign_key "match_scores", "matches", on_delete: :cascade
+  add_foreign_key "match_scores", "teams", on_delete: :cascade
+  add_foreign_key "matches", "groups", on_delete: :cascade
+  add_foreign_key "matches", "stages", on_delete: :cascade
+  add_foreign_key "stages", "tournaments", on_delete: :cascade
+  add_foreign_key "team_action_items", "team_action_lists", on_delete: :cascade
+  add_foreign_key "team_action_items", "teams", on_delete: :cascade
+  add_foreign_key "team_action_lists", "tournaments", on_delete: :cascade
+  add_foreign_key "teams", "tournaments", on_delete: :cascade
+  add_foreign_key "tournament_sync_queue_entries", "tournaments", on_delete: :cascade
+  add_foreign_key "tournaments", "users", on_delete: :cascade
+end
diff --git a/doc/timer_api.md b/doc/timer_api.md
new file mode 100644
index 0000000..dcb1169
--- /dev/null
+++ b/doc/timer_api.md
@@ -0,0 +1,325 @@
+# Tournament Timer API
+
+## Purpose
+
+Backend timer supports:
+
+- countdown mode
+- countup mode
+- clear / unset
+- live websocket updates
+- follower sync propagation
+
+Frontend should treat timer state as:
+
+- no timer: `timestamp = null`, `timer_mode = null`
+- countdown: `timer_mode = "countdown"`
+- countup: `timer_mode = "countup"`
+
+## Read Flow
+
+Timer state is available in normal tournament payload:
+
+- `GET /tournaments/:id`
+
+Dedicated timer endpoint also exists:
+
+- `GET /tournaments/:id/timer`
+
+Response shape:
+
+```json
+{
+  "timestamp": "2026-04-24T10:15:00Z",
+  "timer_mode": "countdown"
+}
+```
+
+Possible values:
+
+- `timer_mode = "countdown"`
+- `timer_mode = "countup"`
+- `timer_mode = null`
+
+## Meaning Of `timestamp`
+
+Same field. Mode decides meaning.
+
+### Countdown mode
+
+`timestamp` means exact wall-clock timestamp when countdown reaches zero.
+
+Frontend math:
+
+```text
+remaining_ms = max(0, timestamp - now)
+```
+
+### Countup mode
+
+`timestamp` means anchor timestamp when countup started.
+
+It is **not** finish time in this mode.
+Think of it as:
+
+- timer start time
+- elapsed-time anchor
+
+Frontend math:
+
+```text
+elapsed_ms = max(0, now - timestamp)
+```
+
+Practical example:
+
+- backend returns:
+  - `timer_mode = "countup"`
+  - `timestamp = "2026-04-24T10:00:00Z"`
+- current time:
+  - `2026-04-24T10:03:15Z`
+
+Frontend should display about `03:15` elapsed.
+
+### Unset timer
+
+- `timer_mode = null`
+- `timestamp = null`
+
+Frontend should render no active timer.
+
+## Write Flow
+
+Only tournament owner may change timer.
+Follower tournaments in `read_only_mode` reject writes with `423`.
+
+Endpoint:
+
+- `PATCH /tournaments/:id/timer`
+
+### Start countdown by duration
+
+Request:
+
+```json
+{
+  "timestamp_seconds": 120
+}
+```
+
+Behavior:
+
+- backend computes `Time.zone.now + 120`
+- backend stores:
+  - `timer_mode = "countdown"`
+  - `timestamp = computed future timestamp`
+
+### Start countdown by explicit timestamp
+
+Request:
+
+```json
+{
+  "timestamp": "2026-04-24T10:15:00Z"
+}
+```
+
+Optional explicit mode:
+
+```json
+{
+  "timestamp": "2026-04-24T10:15:00Z",
+  "timer_mode": "countdown"
+}
+```
+
+### Start countup
+
+Request:
+
+```json
+{
+  "timer_mode": "countup"
+}
+```
+
+Behavior:
+
+- backend stores current server time into `timestamp`
+- backend stores `timer_mode = "countup"`
+
+Frontend should interpret returned `timestamp` as start time anchor.
+
+### Restore countup from explicit anchor
+
+Backend also accepts explicit timestamp with countup mode:
+
+```json
+{
+  "timestamp": "2026-04-24T10:00:00Z",
+  "timer_mode": "countup"
+}
+```
+
+Useful for:
+
+- restoring imported state
+- rehydrating synced follower state
+- advanced admin tooling
+
+### Clear timer
+
+Request:
+
+```json
+{
+  "clear_timer": true
+}
+```
+
+Behavior:
+
+- backend clears both fields
+- response returns:
+  - `timestamp = null`
+  - `timer_mode = null`
+
+## Validation Rules
+
+Backend rejects:
+
+- both `timestamp` and `timestamp_seconds`
+- invalid `timer_mode`
+- `timestamp_seconds <= 0`
+- `timestamp_seconds` together with `timer_mode = "countup"`
+- `timer_mode` by itself unless it is `countup`
+- `clear_timer` mixed with timer values
+
+Countdown timestamps must be future timestamps.
+Countup timestamps may be current or past timestamps.
+
+## Websocket / Live Updates
+
+Timer uses ActionCable websocket broadcast.
+This is websocket push, not webhook callback.
+
+Channel:
+
+- `TournamentTimersChannel`
+
+Subscription identifier:
+
+```json
+{
+  "channel": "TournamentTimersChannel",
+  "tournament_id": 123
+}
+```
+
+Payload:
+
+```json
+{
+  "type": "timer.updated",
+  "tournament_id": 123,
+  "timestamp": "2026-04-24T10:15:00Z",
+  "timer_mode": "countdown"
+}
+```
+
+Behavior:
+
+- subscription immediately receives current timer snapshot
+- later timer changes broadcast full replacement snapshot
+- direct owner edits and follower sync imports both use same broadcast path
+
+Frontend rule:
+
+- replace local timer state from websocket payload
+- do not merge by guessing transitions
+
+## Frontend Implementation Guide
+
+Recommended flow:
+
+1. Load tournament via `GET /tournaments/:id`
+2. Read `timer_mode` and `timestamp`
+3. Open ActionCable subscription for same tournament id
+4. Replace local timer state whenever `timer.updated` arrives
+5. Derive displayed time from `Date.now()` plus stored backend timestamp
+
+Recommended client state:
+
+```ts
+type TimerState =
+  | { mode: null; timestampIso: null }
+  | { mode: "countdown"; timestampIso: string }
+  | { mode: "countup"; timestampIso: string };
+```
+
+Suggested derivation logic:
+
+```ts
+function getTimerDisplay(state: TimerState, nowMs: number) {
+  if (state.mode === null || state.timestampIso === null) {
+    return { active: false, ms: 0 };
+  }
+
+  const timestampMs = new Date(state.timestampIso).getTime();
+
+  if (state.mode === "countdown") {
+    return { active: true, ms: Math.max(0, timestampMs - nowMs) };
+  }
+
+  return { active: true, ms: Math.max(0, nowMs - timestampMs) };
+}
+```
+
+Recommended rendering:
+
+- `countdown`: show remaining time
+- `countup`: show elapsed time
+- unset: hide timer or show inactive state
+
+Recommended local ticking:
+
+- keep backend state as timestamp + mode
+- update rendered value with local interval
+- do not poll backend every second
+
+Recommended write UX:
+
+- owner actions send explicit target request
+- after success, update local state from response body
+- websocket should converge all viewers to same state
+
+## Follower Behavior
+
+Timer state is included in tournament sync snapshots.
+
+That means:
+
+- leader timer changes propagate to follower
+- follower tournament exposes same `timestamp` / `timer_mode`
+- follower websocket subscribers receive `timer.updated`
+- follower still rejects timer writes while read only
+
+## E2E Coverage
+
+Implemented coverage:
+
+- API surface timer lifecycle:
+  - countdown
+  - countup
+  - clear
+  - validation
+  - [spec/e2e/http/api_surface_spec.rb](../spec/e2e/http/api_surface_spec.rb)
+- direct websocket timer updates:
+  - [spec/e2e/http/tournament_timer_websocket_spec.rb](../spec/e2e/http/tournament_timer_websocket_spec.rb)
+- follower websocket timer propagation:
+  - [spec/e2e/http/tournament_timer_follow_sync_websocket_spec.rb](../spec/e2e/http/tournament_timer_follow_sync_websocket_spec.rb)
+
+Current note:
+
+- single-backend HTTP E2E timer specs pass
+- follower blackbox task still has existing Docker/network issue in follow setup, so production-style follow stack verification is not green yet
diff --git a/e2e/lib/action_cable_client.rb b/e2e/lib/action_cable_client.rb
index ff0c4dd..0102ced 100644
--- a/e2e/lib/action_cable_client.rb
+++ b/e2e/lib/action_cable_client.rb
@@ -27,6 +27,17 @@ module TurniereE2E
       end
     end
 
+    def subscribe_timer!(tournament_id:)
+      identifier = {
+        channel: 'TournamentTimersChannel',
+        tournament_id: tournament_id
+      }.to_json
+
+      subscribe!(identifier:) do |message|
+        timer_payload_message?(message)
+      end
+    end
+
     def subscribe_beamer!(tournament_id:, beamer_name:)
       identifier = {
         channel: 'TournamentBeamersChannel',
@@ -41,8 +52,13 @@ module TurniereE2E
 
     def wait_for_payload!(timeout: 20)
       wait_for!(timeout: timeout) do |message|
-        payload = message['message']
-        payload.is_a?(Hash) && payload['type'] == 'team_action_lists.updated'
+        team_action_lists_payload_message?(message)
+      end.fetch('message')
+    end
+
+    def wait_for_timer_payload!(timeout: 20)
+      wait_for!(timeout: timeout) do |message|
+        timer_payload_message?(message)
       end.fetch('message')
     end
 
@@ -169,6 +185,11 @@ module TurniereE2E
       payload.is_a?(Hash) && payload['type'] == 'team_action_lists.updated'
     end
 
+    def timer_payload_message?(message)
+      payload = message['message']
+      payload.is_a?(Hash) && payload['type'] == 'timer.updated'
+    end
+
     def beamer_payload_message?(message)
       payload = message['message']
       payload.is_a?(Hash) && payload['type'].to_s.start_with?('beamer.')
diff --git a/e2e/lib/scenario_runner.rb b/e2e/lib/scenario_runner.rb
index d6d3b24..eb67787 100644
--- a/e2e/lib/scenario_runner.rb
+++ b/e2e/lib/scenario_runner.rb
@@ -29,10 +29,10 @@ module TurniereE2E
       }
 
       timer_response = patch!(
-        "/tournaments/#{tournament.fetch(:id)}/set_timer_end",
-        body: { timer_end_seconds: 600 }
+        "/tournaments/#{tournament.fetch(:id)}/timer",
+        body: { timestamp_seconds: 600 }
       )
-      checkpoints[:timer_set] = { timer_end: timer_response.fetch(:timer_end) }
+      checkpoints[:timer_set] = { timestamp: timer_response.fetch(:timestamp) }
       return result(session: session, tournament: tournament, checkpoints: checkpoints, stop_at: stop_at) if stop_at == :timer_set
 
       upcoming_matches = get!(
diff --git a/spec/controllers/tournaments_controller_spec.rb b/spec/controllers/tournaments_controller_spec.rb
index 65d4dfd..6ba0ed7 100644
--- a/spec/controllers/tournaments_controller_spec.rb
+++ b/spec/controllers/tournaments_controller_spec.rb
@@ -105,7 +105,7 @@ RSpec.describe TournamentsController, type: :controller do
       expected_keys = %i[
         id name code public description playoff_teams_amount
         instant_finalists_amount intermediate_round_participants_amount
-        timer_end owner_username stages teams team_action_lists
+        timestamp timer_mode owner_username stages teams team_action_lists
       ]
       expect(json.keys).to match_array(expected_keys)
       expect(json[:name]).to eq(@tournament.name)
@@ -220,31 +220,63 @@ RSpec.describe TournamentsController, type: :controller do
     end
   end
 
-  describe 'GET #timer_end' do
-    it 'returns timer_end in ISO 8601 format' do
-      timer_end = Time.utc(2026, 4, 13, 18, 0, 0)
-      @tournament.update!(timer_end: timer_end)
+  describe 'GET #timer' do
+    it 'returns timer state in ISO 8601 format' do
+      timestamp = Time.utc(2026, 4, 13, 18, 0, 0)
+      @tournament.update!(timestamp: timestamp, timer_mode: 'countdown')
 
-      get :timer_end, params: { id: @tournament.to_param }
+      get :timer, params: { id: @tournament.to_param }
 
       expect(response).to be_successful
-      expect(deserialize_response(response)[:timer_end]).to eq(timer_end.iso8601)
+      expect(deserialize_response(response)[:timestamp]).to eq(timestamp.iso8601)
+      expect(deserialize_response(response)[:timer_mode]).to eq('countdown')
     end
   end
 
-  describe 'PATCH #set_timer_end' do
+  describe 'PATCH #set_timer' do
     before(:each) do
       apply_authentication_headers_for @user
     end
 
-    it 'stores timezone-aware timer_end values without shifting them' do
-      timer_end = '2030-04-13T18:00:00+02:00'
+    it 'stores timezone-aware timestamp values without shifting them' do
+      timestamp = '2030-04-13T18:00:00+02:00'
 
-      patch :set_timer_end, params: { id: @tournament.to_param, timer_end: timer_end }
+      patch :set_timer, params: { id: @tournament.to_param, timestamp: timestamp }
 
       expect(response).to be_successful
-      expect(@tournament.reload.timer_end.iso8601).to eq(Time.iso8601(timer_end).utc.iso8601)
-      expect(deserialize_response(response)[:timer_end]).to eq(@tournament.timer_end.iso8601)
+      expect(@tournament.reload.timestamp.iso8601).to eq(Time.iso8601(timestamp).utc.iso8601)
+      expect(deserialize_response(response)[:timestamp]).to eq(@tournament.timestamp.iso8601)
+      expect(deserialize_response(response)[:timer_mode]).to eq('countdown')
+    end
+
+    it 'starts countup timer at current time when timer_mode=countup' do
+      before_request = Time.zone.now
+
+      patch :set_timer, params: { id: @tournament.to_param, timer_mode: 'countup' }
+
+      expect(response).to be_successful
+      expect(@tournament.reload.timer_mode).to eq('countup')
+      expect(@tournament.timestamp).to be_between(before_request - 1.second, Time.zone.now + 1.second)
+      expect(deserialize_response(response)[:timer_mode]).to eq('countup')
+    end
+
+    it 'clears timer state when clear_timer=true' do
+      @tournament.update!(timestamp: Time.utc(2030, 4, 13, 18, 0, 0), timer_mode: 'countdown')
+
+      patch :set_timer, params: { id: @tournament.to_param, clear_timer: true }
+
+      expect(response).to be_successful
+      expect(@tournament.reload.timestamp).to be_nil
+      expect(@tournament.timer_mode).to be_nil
+      expect(deserialize_response(response)[:timestamp]).to be_nil
+      expect(deserialize_response(response)[:timer_mode]).to be_nil
+    end
+
+    it 'rejects timestamp_seconds for countup mode' do
+      patch :set_timer, params: { id: @tournament.to_param, timer_mode: 'countup', timestamp_seconds: 120 }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(deserialize_response(response)[:error]).to eq('timestamp_seconds is only allowed for countdown mode')
     end
   end
 
@@ -710,7 +742,7 @@ RSpec.describe TournamentsController, type: :controller do
           playoff_teams_amount: 4,
           instant_finalists_amount: 4,
           intermediate_round_participants_amount: 0,
-          timer_end: nil,
+          timestamp: nil,
           teams: [{ id: 7, name: 'Alpha' }],
           stages: [],
           groups: [],
diff --git a/spec/e2e/http/api_surface_spec.rb b/spec/e2e/http/api_surface_spec.rb
index 7829092..aebfcaf 100644
--- a/spec/e2e/http/api_surface_spec.rb
+++ b/spec/e2e/http/api_surface_spec.rb
@@ -125,15 +125,21 @@ RSpec.describe 'Backend API surface HTTP E2E' do
     forbidden_update = other_client.patch("/tournaments/#{tournament.fetch(:id)}", body: { name: 'Not Allowed' })
     unauthenticated_update = anonymous_client.patch("/tournaments/#{tournament.fetch(:id)}", body: { name: 'No Auth' })
 
-    timer_seconds = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/set_timer_end", body: { timer_end_seconds: 120 })
-    timer_show = anonymous_client.get("/tournaments/#{tournament.fetch(:id)}/timer_end")
-    timer_double = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/set_timer_end", body: {
-                                        timer_end_seconds: 120,
-                                        timer_end: (Time.now.utc + 240).iso8601
+    timer_seconds = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: { timestamp_seconds: 120 })
+    timer_show = anonymous_client.get("/tournaments/#{tournament.fetch(:id)}/timer")
+    timer_countup = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: { timer_mode: 'countup' })
+    timer_clear = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: { clear_timer: true })
+    timer_double = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: {
+                                        timestamp_seconds: 120,
+                                        timestamp: (Time.now.utc + 240).iso8601
                                       })
-    timer_invalid_seconds = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/set_timer_end", body: { timer_end_seconds: 'nope' })
-    timer_past = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/set_timer_end", body: { timer_end_seconds: 0 })
-    timer_forbidden = other_client.patch("/tournaments/#{tournament.fetch(:id)}/set_timer_end", body: { timer_end_seconds: 60 })
+    timer_invalid_seconds = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: { timestamp_seconds: 'nope' })
+    timer_past = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: { timestamp_seconds: 0 })
+    timer_countup_seconds = owner_client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: {
+                                                 timer_mode: 'countup',
+                                                 timestamp_seconds: 60
+                                               })
+    timer_forbidden = other_client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: { timestamp_seconds: 60 })
 
     destroy_response = owner_client.delete("/tournaments/#{tournament.fetch(:id)}")
     after_destroy = anonymous_client.get("/tournaments/#{tournament.fetch(:id)}")
@@ -154,16 +160,26 @@ RSpec.describe 'Backend API surface HTTP E2E' do
     expect(unauthenticated_update[:status]).to eq(401)
 
     expect(timer_seconds[:status]).to eq(200)
-    expect(timer_seconds.dig(:json, :timer_end)).to be_a(String)
+    expect(timer_seconds.dig(:json, :timestamp)).to be_a(String)
+    expect(timer_seconds.dig(:json, :timer_mode)).to eq('countdown')
     expect(timer_show[:status]).to eq(200)
-    expect(timer_show.dig(:json, :timer_end)).to eq(timer_seconds.dig(:json, :timer_end))
+    expect(timer_show.dig(:json, :timestamp)).to eq(timer_seconds.dig(:json, :timestamp))
+    expect(timer_show.dig(:json, :timer_mode)).to eq('countdown')
+    expect(timer_countup[:status]).to eq(200)
+    expect(timer_countup.dig(:json, :timestamp)).to be_a(String)
+    expect(timer_countup.dig(:json, :timer_mode)).to eq('countup')
+    expect(timer_clear[:status]).to eq(200)
+    expect(timer_clear.dig(:json, :timestamp)).to be_nil
+    expect(timer_clear.dig(:json, :timer_mode)).to be_nil
 
     expect(timer_double[:status]).to eq(422)
-    expect(timer_double.dig(:json, :error)).to eq('Only one of timer_end or timer_end_seconds is allowed')
+    expect(timer_double.dig(:json, :error)).to eq('Only one of timestamp or timestamp_seconds is allowed')
     expect(timer_invalid_seconds[:status]).to eq(422)
     expect(timer_invalid_seconds.dig(:json, :error)).to eq('Invalid seconds format')
     expect(timer_past[:status]).to eq(422)
-    expect(timer_past.dig(:json, :error)).to eq('Timer end must be in the future')
+    expect(timer_past.dig(:json, :error)).to eq('Timestamp must be in the future for countdown mode')
+    expect(timer_countup_seconds[:status]).to eq(422)
+    expect(timer_countup_seconds.dig(:json, :error)).to eq('timestamp_seconds is only allowed for countdown mode')
     expect(timer_forbidden[:status]).to eq(403)
 
     expect([200, 204]).to include(destroy_response[:status])
diff --git a/spec/e2e/http/tournament_follow_sync_spec.rb b/spec/e2e/http/tournament_follow_sync_spec.rb
index 7fbd772..1800ad6 100644
--- a/spec/e2e/http/tournament_follow_sync_spec.rb
+++ b/spec/e2e/http/tournament_follow_sync_spec.rb
@@ -503,7 +503,7 @@ RSpec.describe 'Tournament follower sync HTTP E2E' do
       playoff_teams_amount: tournament.fetch(:playoff_teams_amount),
       instant_finalists_amount: tournament.fetch(:instant_finalists_amount),
       intermediate_round_participants_amount: tournament.fetch(:intermediate_round_participants_amount),
-      timer_end: tournament[:timer_end],
+      timestamp: tournament[:timestamp],
       teams: tournament.fetch(:teams).map { |team| team.slice(:name, :advancing_from_group_stage) }.sort_by { |team| team.fetch(:name) },
       team_action_lists: tournament.fetch(:team_action_lists, []).sort_by { |list| list.fetch(:key) }.map do |list|
         {
diff --git a/spec/e2e/http/tournament_timer_follow_sync_websocket_spec.rb b/spec/e2e/http/tournament_timer_follow_sync_websocket_spec.rb
new file mode 100644
index 0000000..3b8c364
--- /dev/null
+++ b/spec/e2e/http/tournament_timer_follow_sync_websocket_spec.rb
@@ -0,0 +1,107 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'securerandom'
+require_relative '../../../e2e/lib/api_client'
+require_relative '../../../e2e/lib/action_cable_client'
+
+RSpec.describe 'Tournament timer follower sync websocket HTTP E2E' do
+  required_env_vars = %w[
+    TURNIERE_E2E_EMAIL
+    TURNIERE_E2E_PASSWORD
+    TURNIERE_SOURCE_E2E_BASE_URL
+    TURNIERE_FOLLOWER_E2E_BASE_URL
+  ].freeze
+
+  before do
+    missing_vars = required_env_vars.reject { |name| ENV.key?(name) }
+    skip("HTTP E2E requires #{missing_vars.join(', ')}") unless missing_vars.empty?
+  end
+
+  let(:source_base_url) { ENV.fetch('TURNIERE_SOURCE_E2E_BASE_URL') }
+  let(:follower_base_url) { ENV.fetch('TURNIERE_FOLLOWER_E2E_BASE_URL') }
+  let(:owner_email) { ENV.fetch('TURNIERE_E2E_EMAIL') }
+  let(:owner_password) { ENV.fetch('TURNIERE_E2E_PASSWORD') }
+  let(:sync_token) { "sync-#{SecureRandom.hex(8)}" }
+  let(:source_client) { login_client(base_url: source_base_url) }
+
+  it 'broadcasts follower timer websocket updates after source sync import' do
+    source = create_playoff_tournament(client: source_client, name_prefix: 'Ws Timer Source')
+    follower = create_follower_tournament(name_prefix: 'Ws Timer Follower')
+
+    configure_sync = source_client.patch("/tournaments/#{source.fetch(:id)}", body: {
+                                           sync_target_url: "#{follower_base_url}/tournaments/#{follower.fetch(:id)}/sync_state",
+                                           sync_auth_token: sync_token
+                                         })
+    expect(configure_sync[:status]).to eq(200)
+
+    cable_client = TurniereE2E::ActionCableClient.new(base_url: follower_base_url)
+    cable_client.subscribe_timer!(tournament_id: follower.fetch(:id))
+    initial_payload = cable_client.wait_for_timer_payload!
+    expect(initial_payload.fetch('timestamp')).to be_nil
+    expect(initial_payload.fetch('timer_mode')).to be_nil
+
+    countdown = source_client.patch("/tournaments/#{source.fetch(:id)}/timer", body: { timestamp_seconds: 120 })
+    expect(countdown[:status]).to eq(200)
+
+    countdown_payload = wait_for_timer_state!(cable_client, timer_mode: 'countdown')
+    expect(countdown_payload.fetch('timestamp')).to eq(countdown.dig(:json, :timestamp))
+
+    countup = source_client.patch("/tournaments/#{source.fetch(:id)}/timer", body: { timer_mode: 'countup' })
+    expect(countup[:status]).to eq(200)
+
+    countup_payload = wait_for_timer_state!(cable_client, timer_mode: 'countup')
+    expect(countup_payload.fetch('timestamp')).to eq(countup.dig(:json, :timestamp))
+
+    clear = source_client.patch("/tournaments/#{source.fetch(:id)}/timer", body: { clear_timer: true })
+    expect(clear[:status]).to eq(200)
+
+    cleared_payload = wait_for_timer_state!(cable_client, timer_mode: nil)
+    expect(cleared_payload.fetch('timestamp')).to be_nil
+  ensure
+    cable_client&.close
+  end
+
+  def login_client(base_url:)
+    client = TurniereE2E::ApiClient.new(base_url: base_url)
+    response = client.login!(email: owner_email, password: owner_password)
+    expect(response[:status]).to eq(200)
+    client
+  end
+
+  def create_playoff_tournament(client:, name_prefix:)
+    response = client.post('/tournaments', body: {
+                             name: "#{name_prefix} #{SecureRandom.hex(3)}",
+                             description: 'Follower websocket timer source tournament',
+                             public: false,
+                             teams: 4.times.map do |index|
+                               { name: "#{name_prefix.tr(' ', '')}-#{index + 1}" }
+                             end
+                           })
+    expect(response[:status]).to eq(201)
+    response.fetch(:json)
+  end
+
+  def create_follower_tournament(name_prefix:)
+    client = login_client(base_url: follower_base_url)
+    response = client.post('/tournaments', body: {
+                             name: "#{name_prefix} #{SecureRandom.hex(3)}",
+                             description: 'Follower websocket timer target tournament',
+                             public: true,
+                             read_only_mode: true,
+                             sync_auth_token: sync_token
+                           })
+    expect(response[:status]).to eq(201)
+    response.fetch(:json)
+  end
+
+  def wait_for_timer_state!(cable_client, timer_mode:, timeout: 20)
+    deadline = Time.now + timeout
+    loop do
+      payload = cable_client.wait_for_timer_payload!(timeout: [deadline - Time.now, 0.1].max)
+      return payload if payload.fetch('timer_mode') == timer_mode
+
+      raise "follower timer websocket payload not received within #{timeout}s" if Time.now >= deadline
+    end
+  end
+end
diff --git a/spec/e2e/http/tournament_timer_websocket_spec.rb b/spec/e2e/http/tournament_timer_websocket_spec.rb
new file mode 100644
index 0000000..1431476
--- /dev/null
+++ b/spec/e2e/http/tournament_timer_websocket_spec.rb
@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'securerandom'
+require_relative '../../../e2e/lib/api_client'
+require_relative '../../../e2e/lib/action_cable_client'
+
+RSpec.describe 'Tournament timer websocket HTTP E2E' do
+  required_env_vars = %w[
+    TURNIERE_E2E_BASE_URL
+    TURNIERE_E2E_EMAIL
+    TURNIERE_E2E_PASSWORD
+  ].freeze
+
+  before do
+    missing_vars = required_env_vars.reject { |name| ENV.key?(name) }
+    skip("HTTP E2E requires #{missing_vars.join(', ')}") unless missing_vars.empty?
+  end
+
+  let(:base_url) { ENV.fetch('TURNIERE_E2E_BASE_URL') }
+  let(:owner_email) { ENV.fetch('TURNIERE_E2E_EMAIL') }
+  let(:owner_password) { ENV.fetch('TURNIERE_E2E_PASSWORD') }
+  let(:client) { login_client }
+
+  it 'broadcasts timer state changes over websocket' do
+    tournament = create_playoff_tournament(name_prefix: 'Ws Timer')
+
+    cable_client = TurniereE2E::ActionCableClient.new(base_url: base_url)
+    cable_client.subscribe_timer!(tournament_id: tournament.fetch(:id))
+
+    initial_payload = cable_client.wait_for_timer_payload!
+    expect(initial_payload.fetch('timestamp')).to be_nil
+    expect(initial_payload.fetch('timer_mode')).to be_nil
+
+    countdown = client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: { timestamp_seconds: 120 })
+    expect(countdown[:status]).to eq(200)
+
+    countdown_payload = wait_for_timer_state!(cable_client, timer_mode: 'countdown')
+    expect(countdown_payload.fetch('timestamp')).to eq(countdown.dig(:json, :timestamp))
+
+    countup = client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: { timer_mode: 'countup' })
+    expect(countup[:status]).to eq(200)
+
+    countup_payload = wait_for_timer_state!(cable_client, timer_mode: 'countup')
+    expect(countup_payload.fetch('timestamp')).to eq(countup.dig(:json, :timestamp))
+
+    clear = client.patch("/tournaments/#{tournament.fetch(:id)}/timer", body: { clear_timer: true })
+    expect(clear[:status]).to eq(200)
+
+    cleared_payload = wait_for_timer_state!(cable_client, timer_mode: nil)
+    expect(cleared_payload.fetch('timestamp')).to be_nil
+  ensure
+    cable_client&.close
+  end
+
+  def login_client
+    api_client = TurniereE2E::ApiClient.new(base_url: base_url)
+    response = api_client.login!(email: owner_email, password: owner_password)
+
+    expect(response[:status]).to eq(200)
+    api_client
+  end
+
+  def create_playoff_tournament(name_prefix:)
+    response = client.post('/tournaments', body: {
+                             name: "#{name_prefix} #{SecureRandom.hex(3)}",
+                             description: 'Websocket timer tournament',
+                             public: false,
+                             teams: 4.times.map do |index|
+                               { name: "#{name_prefix.tr(' ', '')}-#{index + 1}" }
+                             end
+                           })
+    expect(response[:status]).to eq(201)
+    response.fetch(:json)
+  end
+
+  def wait_for_timer_state!(cable_client, timer_mode:, timeout: 20)
+    deadline = Time.now + timeout
+    loop do
+      payload = cable_client.wait_for_timer_payload!(timeout: [deadline - Time.now, 0.1].max)
+      return payload if payload.fetch('timer_mode') == timer_mode
+
+      raise "timer websocket payload not received within #{timeout}s" if Time.now >= deadline
+    end
+  end
+end
diff --git a/spec/services/tournament_snapshot_importer_spec.rb b/spec/services/tournament_snapshot_importer_spec.rb
index e315c18..29292ee 100644
--- a/spec/services/tournament_snapshot_importer_spec.rb
+++ b/spec/services/tournament_snapshot_importer_spec.rb
@@ -18,6 +18,7 @@ RSpec.describe TournamentSnapshotImporter do
       follower.reload
       expect(follower.sync_source_tournament_id).to eq(source.id)
       expect(follower.name).to eq(source.name)
+      expect(follower.timer_mode).to eq(source.timer_mode)
       expect(follower.teams.count).to eq(snapshot.fetch(:teams).count)
       expect(follower.beamers.count).to eq(snapshot.fetch(:beamers).count)
       expect(follower.team_action_lists.count).to eq(snapshot.fetch(:team_action_lists).count)
@@ -182,7 +183,8 @@ RSpec.describe TournamentSnapshotImporter do
       playoff_teams_amount: tournament.playoff_teams_amount,
       instant_finalists_amount: tournament.instant_finalists_amount,
       intermediate_round_participants_amount: tournament.intermediate_round_participants_amount,
-      timer_end: tournament.timer_end&.iso8601,
+      timestamp: tournament.timestamp&.iso8601,
+      timer_mode: tournament.timer_mode,
       teams: tournament.teams.order(:name).map { |team| team.name },
       team_action_lists: tournament.team_action_lists.order(:key).map do |list|
         {
diff --git a/tasks.py b/tasks.py
index e2040cc..6c3fd0e 100644
--- a/tasks.py
+++ b/tasks.py
@@ -1154,7 +1154,7 @@ def docker_blackbox_follow_test(
     ]
     full_command = _docker_compose_cmd(project_name=BLACKBOX_FOLLOW_PROJECT, compose_file=BLACKBOX_FOLLOW_COMPOSE_FILE) + command
     print(_format_command(full_command), flush=True)
-    result = _run_subprocess_live(full_command, env=env, check=False)
+    result = _stream_subprocess(full_command, env=env, check=False)
 
     if result.returncode != 0:
         raise subprocess.CalledProcessError(
@@ -1725,6 +1725,7 @@ def blackbox_follow_service(
         spec_path=[
             "spec/e2e/http/tournament_follow_sync_spec.rb",
             "spec/e2e/http/tournament_follow_sync_websocket_spec.rb",
+            "spec/e2e/http/tournament_timer_follow_sync_websocket_spec.rb",
             "spec/e2e/http/tournament_follow_sync_beamers_websocket_spec.rb",
         ],
         extra_env={