diff --git a/Telegram/CMakeLists.txt b/Telegram/CMakeLists.txt
index 98f8361052..6651b2477c 100644
--- a/Telegram/CMakeLists.txt
+++ b/Telegram/CMakeLists.txt
@@ -163,6 +163,8 @@ PRIVATE
     api/api_premium.h
     api/api_premium_option.cpp
     api/api_premium_option.h
+    api/api_read_metrics.cpp
+    api/api_read_metrics.h
     api/api_report.cpp
     api/api_report.h
     api/api_ringtones.cpp
@@ -965,6 +967,8 @@ PRIVATE
     history/view/history_view_quick_action.h
     history/view/history_view_reaction_preview.cpp
     history/view/history_view_reaction_preview.h
+    history/view/history_view_read_metrics_tracker.cpp
+    history/view/history_view_read_metrics_tracker.h
     history/view/history_view_reply.cpp
     history/view/history_view_reply.h
     history/view/history_view_reply_button.cpp
diff --git a/Telegram/SourceFiles/api/api_read_metrics.cpp b/Telegram/SourceFiles/api/api_read_metrics.cpp
new file mode 100644
index 0000000000..8d2f03c3ef
--- /dev/null
+++ b/Telegram/SourceFiles/api/api_read_metrics.cpp
@@ -0,0 +1,73 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "api/api_read_metrics.h"
+
+#include "apiwrap.h"
+#include "data/data_peer.h"
+
+namespace Api {
+namespace {
+
+constexpr auto kSendTimeout = crl::time(5000);
+
+} // namespace
+
+ReadMetrics::ReadMetrics(not_null<ApiWrap*> api)
+: _api(&api->instance())
+, _timer([=] { send(); }) {
+}
+
+void ReadMetrics::add(
+		not_null<PeerData*> peer,
+		FinalizedReadMetric metric) {
+	_pending[peer].push_back(metric);
+	if (!_timer.isActive()) {
+		_timer.callOnce(kSendTimeout);
+	}
+}
+
+void ReadMetrics::send() {
+	for (auto i = _pending.begin(); i != _pending.end();) {
+		if (_requests.contains(i->first)) {
+			++i;
+			continue;
+		}
+
+		auto metrics = QVector<MTPInputMessageReadMetric>();
+		metrics.reserve(i->second.size());
+		for (const auto &m : i->second) {
+			metrics.push_back(MTP_inputMessageReadMetric(
+				MTP_int(m.msgId.bare),
+				MTP_long(m.viewId),
+				MTP_int(m.timeInViewMs),
+				MTP_int(m.activeTimeInViewMs),
+				MTP_int(m.heightToViewportRatioPermille),
+				MTP_int(m.seenRangeRatioPermille)));
+		}
+		const auto peer = i->first;
+		const auto finish = [=] {
+			_requests.erase(peer);
+			if (!_pending.empty() && !_timer.isActive()) {
+				_timer.callOnce(kSendTimeout);
+			}
+		};
+		const auto requestId = _api.request(MTPmessages_ReportReadMetrics(
+			peer->input(),
+			MTP_vector<MTPInputMessageReadMetric>(std::move(metrics))
+		)).done([=](const MTPBool &) {
+			finish();
+		}).fail([=](const MTP::Error &) {
+			finish();
+		}).send();
+
+		_requests.emplace(peer, requestId);
+		i = _pending.erase(i);
+	}
+}
+
+} // namespace Api
diff --git a/Telegram/SourceFiles/api/api_read_metrics.h b/Telegram/SourceFiles/api/api_read_metrics.h
new file mode 100644
index 0000000000..dcac63db29
--- /dev/null
+++ b/Telegram/SourceFiles/api/api_read_metrics.h
@@ -0,0 +1,45 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+#include "mtproto/sender.h"
+#include "base/timer.h"
+
+class ApiWrap;
+class PeerData;
+
+namespace Api {
+
+struct FinalizedReadMetric {
+	MsgId msgId = 0;
+	uint64 viewId = 0;
+	int timeInViewMs = 0;
+	int activeTimeInViewMs = 0;
+	int heightToViewportRatioPermille = 0;
+	int seenRangeRatioPermille = 0;
+};
+
+class ReadMetrics final {
+public:
+	explicit ReadMetrics(not_null<ApiWrap*> api);
+
+	void add(not_null<PeerData*> peer, FinalizedReadMetric metric);
+
+private:
+	void send();
+
+	MTP::Sender _api;
+	base::flat_map<
+		not_null<PeerData*>,
+		std::vector<FinalizedReadMetric>> _pending;
+	base::flat_map<not_null<PeerData*>, mtpRequestId> _requests;
+	base::Timer _timer;
+
+};
+
+} // namespace Api
diff --git a/Telegram/SourceFiles/apiwrap.cpp b/Telegram/SourceFiles/apiwrap.cpp
index eff428a778..000120ca19 100644
--- a/Telegram/SourceFiles/apiwrap.cpp
+++ b/Telegram/SourceFiles/apiwrap.cpp
@@ -27,6 +27,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "api/api_global_privacy.h"
 #include "api/api_updates.h"
 #include "api/api_user_privacy.h"
+#include "api/api_read_metrics.h"
 #include "api/api_views.h"
 #include "api/api_confirm_phone.h"
 #include "api/api_unread_things.h"
@@ -181,6 +182,7 @@ ApiWrap::ApiWrap(not_null<Main::Session*> session)
 , _inviteLinks(std::make_unique<Api::InviteLinks>(this))
 , _chatLinks(std::make_unique<Api::ChatLinks>(this))
 , _views(std::make_unique<Api::ViewsManager>(this))
+, _readMetrics(std::make_unique<Api::ReadMetrics>(this))
 , _confirmPhone(std::make_unique<Api::ConfirmPhone>(this))
 , _peerPhoto(std::make_unique<Api::PeerPhoto>(this))
 , _polls(std::make_unique<Api::Polls>(this))
@@ -4976,6 +4978,10 @@ Api::ViewsManager &ApiWrap::views() {
 	return *_views;
 }
 
+Api::ReadMetrics &ApiWrap::readMetrics() {
+	return *_readMetrics;
+}
+
 Api::ConfirmPhone &ApiWrap::confirmPhone() {
 	return *_confirmPhone;
 }
diff --git a/Telegram/SourceFiles/apiwrap.h b/Telegram/SourceFiles/apiwrap.h
index 52e846525b..19e43e5d3a 100644
--- a/Telegram/SourceFiles/apiwrap.h
+++ b/Telegram/SourceFiles/apiwrap.h
@@ -83,6 +83,7 @@ class UnreadThings;
 class Ringtones;
 class Transcribes;
 class Premium;
+class ReadMetrics;
 class Usernames;
 class Websites;
 
@@ -414,6 +415,7 @@ public:
 	[[nodiscard]] Api::InviteLinks &inviteLinks();
 	[[nodiscard]] Api::ChatLinks &chatLinks();
 	[[nodiscard]] Api::ViewsManager &views();
+	[[nodiscard]] Api::ReadMetrics &readMetrics();
 	[[nodiscard]] Api::ConfirmPhone &confirmPhone();
 	[[nodiscard]] Api::PeerPhoto &peerPhoto();
 	[[nodiscard]] Api::Polls &polls();
@@ -772,6 +774,7 @@ private:
 	const std::unique_ptr<Api::InviteLinks> _inviteLinks;
 	const std::unique_ptr<Api::ChatLinks> _chatLinks;
 	const std::unique_ptr<Api::ViewsManager> _views;
+	const std::unique_ptr<Api::ReadMetrics> _readMetrics;
 	const std::unique_ptr<Api::ConfirmPhone> _confirmPhone;
 	const std::unique_ptr<Api::PeerPhoto> _peerPhoto;
 	const std::unique_ptr<Api::Polls> _polls;
diff --git a/Telegram/SourceFiles/core/application.cpp b/Telegram/SourceFiles/core/application.cpp
index 9b5835b6c7..46508d3da6 100644
--- a/Telegram/SourceFiles/core/application.cpp
+++ b/Telegram/SourceFiles/core/application.cpp
@@ -645,6 +645,7 @@ bool Application::eventFilter(QObject *object, QEvent *e) {
 	switch (e->type()) {
 	case QEvent::KeyPress: {
 		updateNonIdle();
+		_inAppKeyPressed.fire({});
 		const auto event = static_cast<QKeyEvent*>(e);
 		if (base::Platform::GlobalShortcuts::IsToggleFullScreenKey(event)
 			&& toggleActiveWindowFullScreen()) {
@@ -1224,6 +1225,10 @@ crl::time Application::lastNonIdleTime() const {
 		_lastNonIdleTime);
 }
 
+rpl::producer<> Application::inAppKeyPressed() const {
+	return _inAppKeyPressed.events();
+}
+
 rpl::producer<bool> Application::passcodeLockChanges() const {
 	return _passcodeLock.changes();
 }
diff --git a/Telegram/SourceFiles/core/application.h b/Telegram/SourceFiles/core/application.h
index 15f514582e..4ce78c8074 100644
--- a/Telegram/SourceFiles/core/application.h
+++ b/Telegram/SourceFiles/core/application.h
@@ -329,6 +329,7 @@ public:
 	void handleAppActivated();
 	void handleAppDeactivated();
 	[[nodiscard]] rpl::producer<bool> appDeactivatedValue() const;
+	[[nodiscard]] rpl::producer<> inAppKeyPressed() const;
 
 	void materializeLocalDrafts();
 	[[nodiscard]] rpl::producer<> materializeLocalDraftsRequests() const;
@@ -464,6 +465,7 @@ private:
 	base::flat_map<not_null<QWidget*>, LeaveFilter> _leaveFilters;
 
 	rpl::event_stream<Media::View::OpenRequest> _openInMediaViewRequests;
+	rpl::event_stream<> _inAppKeyPressed;
 
 	rpl::event_stream<> _materializeLocalDraftsRequests;
 
diff --git a/Telegram/SourceFiles/history/history_inner_widget.cpp b/Telegram/SourceFiles/history/history_inner_widget.cpp
index c513b268fd..79dff4163f 100644
--- a/Telegram/SourceFiles/history/history_inner_widget.cpp
+++ b/Telegram/SourceFiles/history/history_inner_widget.cpp
@@ -8,6 +8,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "history/history_inner_widget.h"
 
 #include "chat_helpers/stickers_emoji_pack.h"
+#include "core/application.h"
 #include "core/file_utilities.h"
 #include "core/click_handler_types.h"
 #include "core/phone_click_handler.h"
@@ -69,6 +70,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "chat_helpers/emoji_interactions.h"
 #include "history/history_widget.h"
 #include "history/view/history_view_translate_tracker.h"
+#include "history/view/history_view_read_metrics_tracker.h"
 #include "base/platform/base_platform_info.h"
 #include "base/qt/qt_common_adapters.h"
 #include "base/qt/qt_key_modifiers.h"
@@ -111,6 +113,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include <QtGui/QClipboard>
 #include <QtWidgets/QApplication>
+#include <QtCore/QCoreApplication>
 #include <QtCore/QMimeData>
 
 namespace {
@@ -325,6 +328,8 @@ HistoryInner::HistoryInner(
 	[=](not_null<const Element*> view) { return itemTop(view); }))
 , _migrated(history->migrateFrom())
 , _translateTracker(std::make_unique<HistoryView::TranslateTracker>(history))
+, _readMetricsTracker(std::make_unique<HistoryView::ReadMetricsTracker>(
+	_peer))
 , _pathGradient(
 	HistoryView::MakePathShiftGradient(
 		controller->chatStyle(),
@@ -365,6 +370,10 @@ HistoryInner::HistoryInner(
 	refreshAboutView();
 
 	setMouseTracking(true);
+	Core::App().inAppKeyPressed(
+	) | rpl::on_next([=] {
+		registerReadMetricsActivity();
+	}, lifetime());
 	_controller->gifPauseLevelChanged(
 	) | rpl::on_next([=] {
 		if (!elementAnimationsPaused()) {
@@ -419,9 +428,12 @@ HistoryInner::HistoryInner(
 	}, lifetime());
 	session().data().viewLayoutChanged(
 	) | rpl::filter([=](not_null<const Element*> view) {
-		return (view == viewByItem(view->data())) && view->isUnderCursor();
+		return (view == viewByItem(view->data()));
 	}) | rpl::on_next([=](not_null<const Element*> view) {
-		mouseActionUpdate();
+		markReadMetricsStale();
+		if (view->isUnderCursor()) {
+			mouseActionUpdate();
+		}
 	}, lifetime());
 
 	session().data().itemDataChanges(
@@ -1134,8 +1146,12 @@ void HistoryInner::startEffectOnRead(not_null<HistoryItem*> item) {
 }
 
 void HistoryInner::paintEvent(QPaintEvent *e) {
-	if (_controller->contentOverlapped(this, e)
-		|| hasPendingResizedItems()) {
+	const auto overlapped = _controller->contentOverlapped(this, e);
+	const auto pendingResized = hasPendingResizedItems();
+	_readMetricsTracker->setScreenActive(!overlapped
+		&& !pendingResized
+		&& _widget->markingContentsRead());
+	if (overlapped || pendingResized) {
 		return;
 	} else if (_recountedAfterPendingResizedItems) {
 		_recountedAfterPendingResizedItems = false;
@@ -1179,6 +1195,10 @@ void HistoryInner::paintEvent(QPaintEvent *e) {
 	}
 
 	_translateTracker->startBunch();
+	const auto metricsStale = base::take(_readMetricsStale);
+	if (metricsStale) {
+		_readMetricsTracker->startBatch(_visibleAreaTop, _visibleAreaBottom);
+	}
 	auto readTill = (HistoryItem*)nullptr;
 	auto readContents = base::flat_set<not_null<HistoryItem*>>();
 	auto startEffects = base::flat_set<not_null<const Element*>>();
@@ -1187,6 +1207,9 @@ void HistoryInner::paintEvent(QPaintEvent *e) {
 		if (_pinnedItem) {
 			_translateTracker->add(_pinnedItem);
 		}
+		if (metricsStale) {
+			_readMetricsTracker->endBatch();
+		}
 		_translateTracker->finishBunch();
 		if (!startEffects.empty()) {
 			for (const auto &view : startEffects) {
@@ -1208,6 +1231,9 @@ void HistoryInner::paintEvent(QPaintEvent *e) {
 			int height) {
 		_translateTracker->add(view);
 		const auto item = view->data();
+		if (metricsStale && height > 0) {
+			_readMetricsTracker->push(item, top, height);
+		}
 		const auto isSponsored = item->isSponsored();
 		const auto isUnread = !item->out()
 			&& item->unread(_history)
@@ -1670,6 +1696,7 @@ void HistoryInner::touchEvent(QTouchEvent *e) {
 		_touchPrevPos = _touchPos;
 		_touchPos = e->touchPoints().cbegin()->screenPos().toPoint();
 	}
+	registerReadMetricsActivity();
 
 	switch (e->type()) {
 	case QEvent::TouchBegin: {
@@ -1792,6 +1819,7 @@ void HistoryInner::mouseMoveEvent(QMouseEvent *e) {
 	}
 	if (reallyMoved) {
 		_mouseActive = true;
+		registerReadMetricsActivity();
 		lastGlobalPosition = e->globalPos();
 		if (!buttonsPressed || (_scrollDateLink && ClickHandler::getPressed() == _scrollDateLink)) {
 			keepScrollDateForNow();
@@ -1851,6 +1879,7 @@ void HistoryInner::mousePressEvent(QMouseEvent *e) {
 		return;
 	}
 	_mouseActive = true;
+	registerReadMetricsActivity();
 	mouseActionStart(e->globalPos(), e->button());
 }
 
@@ -2279,6 +2308,7 @@ void HistoryInner::mouseReleaseEvent(QMouseEvent *e) {
 		e->accept();
 		return;
 	}
+	registerReadMetricsActivity();
 	mouseActionFinish(e->globalPos(), e->button());
 	if (!rect().contains(e->pos())) {
 		leaveEvent(e);
@@ -2286,6 +2316,7 @@ void HistoryInner::mouseReleaseEvent(QMouseEvent *e) {
 }
 
 void HistoryInner::mouseDoubleClickEvent(QMouseEvent *e) {
+	registerReadMetricsActivity();
 	mouseActionStart(e->globalPos(), e->button());
 
 	const auto mouseActionView = viewByItem(_mouseActionItem);
@@ -3641,6 +3672,17 @@ void HistoryInner::keyPressEvent(QKeyEvent *e) {
 	}
 }
 
+void HistoryInner::markReadMetricsStale() {
+	_readMetricsStale = true;
+	update();
+}
+
+void HistoryInner::registerReadMetricsActivity() {
+	if (_widget->markingContentsRead()) {
+		_readMetricsTracker->registerActivity();
+	}
+}
+
 void HistoryInner::checkActivation() {
 	if (!_widget->markingMessagesRead()) {
 		return;
@@ -3771,6 +3813,8 @@ void HistoryInner::visibleAreaUpdated(int top, int bottom) {
 	auto scrolledUp = (top < _visibleAreaTop);
 	_visibleAreaTop = top;
 	_visibleAreaBottom = bottom;
+	markReadMetricsStale();
+	registerReadMetricsActivity();
 	const auto visibleAreaHeight = bottom - top;
 
 	// if history has pending resize events we should not update scrollTopItem
diff --git a/Telegram/SourceFiles/history/history_inner_widget.h b/Telegram/SourceFiles/history/history_inner_widget.h
index de07761685..60781aaa05 100644
--- a/Telegram/SourceFiles/history/history_inner_widget.h
+++ b/Telegram/SourceFiles/history/history_inner_widget.h
@@ -40,6 +40,7 @@ enum class ElementChatMode : char;
 class EmptyPainter;
 class Element;
 class TranslateTracker;
+class ReadMetricsTracker;
 struct PinnedId;
 struct SelectedQuote;
 class AboutView;
@@ -256,6 +257,8 @@ protected:
 private:
 	void onTouchSelect();
 	void onTouchScrollTimer();
+	void markReadMetricsStale();
+	void registerReadMetricsActivity();
 
 	[[nodiscard]] static int SelectionViewOffset(
 		not_null<const HistoryInner*> inner,
@@ -497,6 +500,8 @@ private:
 	std::unique_ptr<HistoryView::AboutView> _aboutView;
 	std::unique_ptr<HistoryView::EmptyPainter> _emptyPainter;
 	std::unique_ptr<HistoryView::TranslateTracker> _translateTracker;
+	std::unique_ptr<HistoryView::ReadMetricsTracker> _readMetricsTracker;
+	bool _readMetricsStale = false;
 	rpl::event_stream<not_null<DocumentData*>> _sendIntroSticker;
 
 	mutable History *_curHistory = nullptr;
diff --git a/Telegram/SourceFiles/history/view/history_view_list_widget.cpp b/Telegram/SourceFiles/history/view/history_view_list_widget.cpp
index 01d49dfaa5..4ef8b40ab3 100644
--- a/Telegram/SourceFiles/history/view/history_view_list_widget.cpp
+++ b/Telegram/SourceFiles/history/view/history_view_list_widget.cpp
@@ -10,6 +10,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "base/unixtime.h"
 #include "base/qt/qt_key_modifiers.h"
 #include "base/qt/qt_common_adapters.h"
+#include "history/history.h"
 #include "history/history_item.h"
 #include "history/history_item_components.h"
 #include "history/history_item_helpers.h"
@@ -27,6 +28,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "history/view/history_view_service_message.h"
 #include "history/view/history_view_cursor_state.h"
 #include "history/view/history_view_translate_tracker.h"
+#include "history/view/history_view_read_metrics_tracker.h"
 #include "history/view/history_view_top_peers_selector.h"
 #include "history/view/history_view_quick_action.h"
 #include "chat_helpers/message_field.h"
@@ -99,6 +101,16 @@ constexpr auto kClearUserpicsAfter = 50;
 	return history ? std::make_unique<TranslateTracker>(history) : nullptr;
 }
 
+[[nodiscard]] std::unique_ptr<ReadMetricsTracker> MaybeReadMetricsTracker(
+		Context context,
+		History *history) {
+	if (!history
+		|| (context != Context::History && context != Context::Replies)) {
+		return nullptr;
+	}
+	return std::make_unique<ReadMetricsTracker>(history->peer);
+}
+
 } // namespace
 
 WindowListDelegate::WindowListDelegate(
@@ -409,6 +421,9 @@ ListWidget::ListWidget(
 , _replyButtonManager(std::make_unique<ReplyButton::Manager>(
 	[=](QRect updated) { update(updated); }))
 , _translateTracker(MaybeTranslateTracker(_delegate->listTranslateHistory()))
+, _readMetricsTracker(MaybeReadMetricsTracker(
+	_delegate->listContext(),
+	_delegate->listTranslateHistory()))
 , _scrollDateCheck([this] { scrollDateCheck(); })
 , _applyUpdatedScrollState([this] { applyUpdatedScrollState(); })
 , _selectEnabled(_delegate->listAllowsMultiSelect())
@@ -419,12 +434,19 @@ ListWidget::ListWidget(
 , _touchSelectTimer([=] { onTouchSelect(); })
 , _touchScrollTimer([=] { onTouchScrollTimer(); })
 , _middleClickAutoscroll(
-	[=](int d) { _delegate->listScrollTo(_visibleTop + d, false); },
-	[=](const QCursor &cursor) { setCursor(cursor); },
-	[=] { mouseActionUpdate(QCursor::pos()); setCursor(_cursor); },
-	[=] { return window()->isActiveWindow(); }) {
+		[=](int d) { _delegate->listScrollTo(_visibleTop + d, false); },
+		[=](const QCursor &cursor) { setCursor(cursor); },
+		[=] { mouseActionUpdate(QCursor::pos()); setCursor(_cursor); },
+		[=] { return window()->isActiveWindow(); }) {
 	setAttribute(Qt::WA_AcceptTouchEvents);
 	setMouseTracking(true);
+	if (_readMetricsTracker) {
+		Core::App().inAppKeyPressed(
+		) | rpl::on_next([=] {
+			registerReadMetricsActivity();
+		}, lifetime());
+	}
+
 	_scrollDateHideTimer.setCallback([this] { scrollDateHideByTimer(); });
 	_session->data().viewRepaintRequest(
 	) | rpl::on_next([this](Data::RequestViewRepaint data) {
@@ -451,6 +473,7 @@ ListWidget::ListWidget(
 	_session->data().viewLayoutChanged(
 	) | rpl::on_next([this](auto view) {
 		if (view->delegate() == this) {
+			markReadMetricsStale();
 			if (view->isUnderCursor()) {
 				mouseActionUpdate();
 			}
@@ -1112,29 +1135,6 @@ int ListWidget::findNearestItem(Data::MessagePosition position) const {
 		: int(after - begin(_items));
 }
 
-HistoryItemsList ListWidget::collectVisibleItems() const {
-	auto result = HistoryItemsList();
-	const auto from = std::lower_bound(
-		begin(_items),
-		end(_items),
-		_visibleTop,
-		[this](auto &elem, int top) {
-			return this->itemTop(elem) + elem->height() <= top;
-		});
-	const auto to = std::lower_bound(
-		begin(_items),
-		end(_items),
-		_visibleBottom,
-		[this](auto &elem, int bottom) {
-			return this->itemTop(elem) < bottom;
-		});
-	result.reserve(to - from);
-	for (auto i = from; i != to; ++i) {
-		result.push_back((*i)->data());
-	}
-	return result;
-}
-
 void ListWidget::visibleTopBottomUpdated(
 		int visibleTop,
 		int visibleBottom) {
@@ -1146,6 +1146,8 @@ void ListWidget::visibleTopBottomUpdated(
 	const auto scrolledUp = (visibleTop < _visibleTop);
 	_visibleTop = visibleTop;
 	_visibleBottom = visibleBottom;
+	markReadMetricsStale();
+	registerReadMetricsActivity();
 
 	// Unload userpics.
 	if (_userpics.size() > kClearUserpicsAfter) {
@@ -2274,11 +2276,21 @@ void ListWidget::checkActivation() {
 }
 
 void ListWidget::paintEvent(QPaintEvent *e) {
-	if (_delegate->listIgnorePaintEvent(this, e)) {
+	const auto overlapped = _delegate->listIgnorePaintEvent(this, e);
+	if (_readMetricsTracker) {
+		_readMetricsTracker->setScreenActive(
+			!overlapped && markingContentsRead());
+	}
+	if (overlapped) {
 		return;
 	} else if (_translateTracker) {
 		_translateTracker->startBunch();
 	}
+	const auto metricsStale = _readMetricsTracker
+		&& base::take(_readMetricsStale);
+	if (metricsStale) {
+		_readMetricsTracker->startBatch(_visibleTop, _visibleBottom);
+	}
 	auto readTill = (HistoryItem*)nullptr;
 	auto readContents = base::flat_set<not_null<HistoryItem*>>();
 	const auto markingAsViewed = markingMessagesRead();
@@ -2287,6 +2299,9 @@ void ListWidget::paintEvent(QPaintEvent *e) {
 			_delegate->listAddTranslatedItems(_translateTracker.get());
 			_translateTracker->finishBunch();
 		}
+		if (metricsStale) {
+			_readMetricsTracker->endBatch();
+		}
 		if (markingAsViewed && readTill) {
 			_delegate->listMarkReadTill(readTill);
 		}
@@ -2345,6 +2360,9 @@ void ListWidget::paintEvent(QPaintEvent *e) {
 		if (_translateTracker) {
 			_translateTracker->add(view);
 		}
+		if (metricsStale && height > 0) {
+			_readMetricsTracker->push(item, top, height);
+		}
 		const auto isSponsored = item->isSponsored();
 		const auto isUnread = _delegate->listElementShownUnread(view)
 			&& item->isRegular();
@@ -2770,6 +2788,7 @@ auto ListWidget::scrollKeyEvents() const
 }
 
 void ListWidget::mouseDoubleClickEvent(QMouseEvent *e) {
+	registerReadMetricsActivity();
 	mouseActionStart(e->globalPos(), e->button());
 	trySwitchToWordSelection();
 	if (!ClickHandler::getActive()
@@ -3057,6 +3076,7 @@ void ListWidget::mousePressEvent(QMouseEvent *e) {
 		return;
 	}
 	_mouseActive = true;
+	registerReadMetricsActivity();
 	mouseActionStart(e->globalPos(), e->button());
 }
 
@@ -3160,6 +3180,7 @@ void ListWidget::touchEvent(QTouchEvent *e) {
 		_touchPrevPos = _touchPos;
 		_touchPos = e->touchPoints().cbegin()->screenPos().toPoint();
 	}
+	registerReadMetricsActivity();
 
 	switch (e->type()) {
 	case QEvent::TouchBegin: {
@@ -3273,6 +3294,7 @@ void ListWidget::mouseMoveEvent(QMouseEvent *e) {
 	}
 	if (reallyMoved) {
 		_mouseActive = true;
+		registerReadMetricsActivity();
 		lastGlobalPosition = e->globalPos();
 		if (!buttonsPressed
 			|| (_scrollDateLink
@@ -3292,12 +3314,24 @@ void ListWidget::mouseReleaseEvent(QMouseEvent *e) {
 		e->accept();
 		return;
 	}
+	registerReadMetricsActivity();
 	mouseActionFinish(e->globalPos(), e->button());
 	if (!rect().contains(e->pos())) {
 		leaveEvent(e);
 	}
 }
 
+void ListWidget::markReadMetricsStale() {
+	_readMetricsStale = true;
+	update();
+}
+
+void ListWidget::registerReadMetricsActivity() {
+	if (_readMetricsTracker && markingContentsRead()) {
+		_readMetricsTracker->registerActivity();
+	}
+}
+
 void ListWidget::touchScrollUpdated(const QPoint &screenPos) {
 	_touchPos = screenPos;
 	_delegate->listScrollTo(
diff --git a/Telegram/SourceFiles/history/view/history_view_list_widget.h b/Telegram/SourceFiles/history/view/history_view_list_widget.h
index 8de6f9682b..c8a4834194 100644
--- a/Telegram/SourceFiles/history/view/history_view_list_widget.h
+++ b/Telegram/SourceFiles/history/view/history_view_list_widget.h
@@ -68,6 +68,7 @@ struct TextState;
 struct StateRequest;
 class EmojiInteractions;
 class TranslateTracker;
+class ReadMetricsTracker;
 enum class CursorState : char;
 enum class PointState : char;
 enum class Context : char;
@@ -541,6 +542,8 @@ private:
 
 	void onTouchSelect();
 	void onTouchScrollTimer();
+	void markReadMetricsStale();
+	void registerReadMetricsActivity();
 
 	void updateAroundPositionFromNearest(int nearestIndex);
 	void refreshRows(const Data::MessagesSlice &old);
@@ -599,7 +602,6 @@ private:
 	[[nodiscard]] Element *strictFindItemByY(int y) const;
 	[[nodiscard]] int findNearestItem(Data::MessagePosition position) const;
 	void viewReplaced(not_null<const Element*> was, Element *now);
-	[[nodiscard]] HistoryItemsList collectVisibleItems() const;
 
 	void checkMoveToOtherViewer();
 	void updateVisibleTopItem();
@@ -794,6 +796,8 @@ private:
 	std::unique_ptr<ReplyButton::Manager> _replyButtonManager;
 
 	std::unique_ptr<TranslateTracker> _translateTracker;
+	std::unique_ptr<ReadMetricsTracker> _readMetricsTracker;
+	bool _readMetricsStale = false;
 
 	int _minHeight = 0;
 	int _visibleTop = 0;
diff --git a/Telegram/SourceFiles/history/view/history_view_read_metrics_tracker.cpp b/Telegram/SourceFiles/history/view/history_view_read_metrics_tracker.cpp
new file mode 100644
index 0000000000..3956be11f9
--- /dev/null
+++ b/Telegram/SourceFiles/history/view/history_view_read_metrics_tracker.cpp
@@ -0,0 +1,353 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "history/view/history_view_read_metrics_tracker.h"
+
+#include "api/api_read_metrics.h"
+#include "apiwrap.h"
+#include "base/random.h"
+#include "core/application.h"
+#include "data/data_peer.h"
+#include "history/history_item.h"
+#include "main/main_session.h"
+
+namespace HistoryView {
+namespace {
+
+constexpr auto kGracePeriod = crl::time(300);
+constexpr auto kActivityTimeout = 15 * crl::time(1000);
+constexpr auto kMaxTrackingDuration = 5 * 60 * crl::time(1000);
+constexpr auto kMinReportThreshold = crl::time(300);
+
+} // namespace
+
+ReadMetricsTracker::ReadMetricsTracker(not_null<PeerData*> peer)
+: _peer(peer)
+, _timer([=] { onTimeout(); }) {
+	Core::App().appDeactivatedValue(
+	) | rpl::on_next([=](bool deactivated) {
+		const auto appActive = !deactivated;
+		if (_appActive == appActive) {
+			return;
+		}
+		_appActive = appActive;
+		refreshPaused(crl::now());
+	}, _lifetime);
+}
+
+ReadMetricsTracker::~ReadMetricsTracker() {
+	finalizeAll();
+}
+
+void ReadMetricsTracker::startBatch(int visibleTop, int visibleBottom) {
+	_batchNow = crl::now();
+	sync(_batchNow);
+	_batchViewportHeight = visibleBottom - visibleTop;
+	_batchVisibleTop = visibleTop;
+	_batchVisibleBottom = visibleBottom;
+	_batchVisible.clear();
+}
+
+void ReadMetricsTracker::push(
+		not_null<HistoryItem*> item,
+		int itemTop,
+		int itemHeight) {
+	if (!ShouldTrack(item)) {
+		return;
+	}
+	const auto msgId = item->id;
+	_batchVisible.emplace(msgId);
+
+	const auto clippedTop = std::max(itemTop, _batchVisibleTop) - itemTop;
+	const auto clippedBottom = std::min(
+		itemTop + itemHeight,
+		_batchVisibleBottom) - itemTop;
+
+	const auto addTracked = [&] {
+		auto tracked = TrackedItem();
+		tracked.entryGracePending = true;
+		tracked.entryGraceStart = _batchNow;
+		tracked.maxItemHeight = itemHeight;
+		tracked.maxViewportHeight = _batchViewportHeight;
+		tracked.seenTop = clippedTop;
+		tracked.seenBottom = clippedBottom;
+		_tracked.emplace(msgId, tracked);
+	};
+
+	auto it = _tracked.find(msgId);
+	if (it == end(_tracked)) {
+		addTracked();
+		return;
+	}
+	auto &tracked = it->second;
+	if (tracked.exitGracePending) {
+		if (_batchNow - tracked.exitGraceStart >= kGracePeriod) {
+			finalize(msgId, tracked);
+			_tracked.erase(it);
+			addTracked();
+			return;
+		}
+		tracked.exitGracePending = false;
+		tracked.exitGraceStart = 0;
+		tracked.lastUpdate = _batchNow;
+	}
+	tracked.seenTop = std::min(tracked.seenTop, clippedTop);
+	tracked.seenBottom = std::max(tracked.seenBottom, clippedBottom);
+	accumulate_max(tracked.maxItemHeight, itemHeight);
+	accumulate_max(tracked.maxViewportHeight, _batchViewportHeight);
+}
+
+void ReadMetricsTracker::endBatch() {
+	for (auto it = _tracked.begin(); it != _tracked.end();) {
+		if (_batchVisible.contains(it->first)) {
+			++it;
+			continue;
+		}
+		auto &tracked = it->second;
+		if (tracked.entryGracePending) {
+			it = _tracked.erase(it);
+			continue;
+		}
+		if (!tracked.exitGracePending) {
+			tracked.exitGracePending = true;
+			tracked.exitGraceStart = _batchNow;
+		}
+		++it;
+	}
+
+	_currentlyVisible = std::move(_batchVisible);
+	restartTimer();
+}
+
+void ReadMetricsTracker::registerActivity() {
+	if (!_appActive || !_screenActive) {
+		return;
+	}
+	const auto now = crl::now();
+	const auto activityDeadline = activeUntil();
+	if (activityDeadline && activityDeadline < now) {
+		sync(now);
+	}
+	_lastActivity = now;
+	restartTimer();
+}
+
+void ReadMetricsTracker::setScreenActive(bool active) {
+	if (_screenActive == active) {
+		return;
+	}
+	_screenActive = active;
+	refreshPaused(crl::now());
+}
+
+void ReadMetricsTracker::pauseTracking() {
+	setScreenActive(false);
+}
+
+void ReadMetricsTracker::resumeTracking() {
+	setScreenActive(true);
+}
+
+void ReadMetricsTracker::onTimeout() {
+	sync(crl::now());
+}
+
+void ReadMetricsTracker::sync(crl::time now) {
+	const auto activeUntil = this->activeUntil();
+	processTransitions(now, activeUntil);
+	accumulate(now, activeUntil);
+	restartTimer();
+}
+
+void ReadMetricsTracker::processTransitions(
+		crl::time now,
+		crl::time activeUntil) {
+	for (auto it = _tracked.begin(); it != _tracked.end();) {
+		auto &tracked = it->second;
+		if (tracked.entryGracePending
+			&& !_paused
+			&& now - tracked.entryGraceStart >= kGracePeriod) {
+			tracked.entryGracePending = false;
+			do {
+				tracked.viewId = base::RandomValue<uint64>();
+			} while (!tracked.viewId);
+			tracked.trackingStarted = tracked.entryGraceStart;
+			tracked.lastUpdate = tracked.trackingStarted;
+		}
+		if (tracked.exitGracePending
+			&& !_paused
+			&& now - tracked.exitGraceStart >= kGracePeriod) {
+			finalize(it->first, tracked);
+			it = _tracked.erase(it);
+			continue;
+		}
+		if (tracked.viewId && !tracked.entryGracePending && !tracked.exitGracePending) {
+			const auto deadline = tracked.trackingStarted + kMaxTrackingDuration;
+			if (now >= deadline) {
+				if (!_paused
+					&& _currentlyVisible.contains(it->first)
+					&& tracked.lastUpdate < deadline) {
+					addElapsed(tracked, tracked.lastUpdate, deadline, activeUntil);
+					tracked.lastUpdate = deadline;
+				}
+				finalize(it->first, tracked);
+				it = _tracked.erase(it);
+				continue;
+			}
+		}
+		++it;
+	}
+}
+
+void ReadMetricsTracker::accumulate(crl::time now, crl::time activeUntil) {
+	for (auto &[msgId, tracked] : _tracked) {
+		if (!tracked.viewId
+			|| tracked.entryGracePending
+			|| tracked.exitGracePending
+			|| tracked.lastUpdate <= 0) {
+			continue;
+		}
+		if (_paused || !_currentlyVisible.contains(msgId)) {
+			tracked.lastUpdate = now;
+			continue;
+		}
+		addElapsed(tracked, tracked.lastUpdate, now, activeUntil);
+		tracked.lastUpdate = now;
+	}
+}
+
+void ReadMetricsTracker::refreshPaused(crl::time now) {
+	const auto paused = !_appActive || !_screenActive;
+	if (_paused == paused) {
+		return;
+	} else if (paused) {
+		const auto activeUntil = this->activeUntil();
+		processTransitions(now, activeUntil);
+		accumulate(now, activeUntil);
+		_pausedSince = now;
+		for (auto &[msgId, tracked] : _tracked) {
+			if (tracked.entryGracePending || tracked.exitGracePending) {
+				continue;
+			}
+			tracked.lastUpdate = now;
+		}
+	} else {
+		const auto delta = now - _pausedSince;
+		for (auto &[msgId, tracked] : _tracked) {
+			if (tracked.entryGracePending) {
+				tracked.entryGraceStart = (tracked.entryGraceStart < _pausedSince)
+					? (tracked.entryGraceStart + delta)
+					: now;
+			} else if (tracked.exitGracePending) {
+				tracked.exitGraceStart = (tracked.exitGraceStart < _pausedSince)
+					? (tracked.exitGraceStart + delta)
+					: now;
+			} else if (tracked.viewId) {
+				tracked.lastUpdate = now;
+			}
+		}
+		_pausedSince = 0;
+	}
+	_paused = paused;
+	restartTimer();
+}
+
+void ReadMetricsTracker::restartTimer() {
+	if (_tracked.empty()) {
+		_timer.cancel();
+		return;
+	}
+	const auto now = crl::now();
+	auto nearest = crl::time(0);
+	const auto updateNearest = [&](crl::time deadline) {
+		if (!deadline) {
+			return;
+		}
+		if (!nearest || deadline < nearest) {
+			nearest = deadline;
+		}
+	};
+
+	const auto activityDeadline = activeUntil();
+	for (const auto &[msgId, tracked] : _tracked) {
+		if (tracked.entryGracePending && !_paused) {
+			updateNearest(tracked.entryGraceStart + kGracePeriod);
+		} else if (tracked.exitGracePending && !_paused) {
+			updateNearest(tracked.exitGraceStart + kGracePeriod);
+		} else if (tracked.viewId) {
+			updateNearest(tracked.trackingStarted + kMaxTrackingDuration);
+			if (!_paused && _currentlyVisible.contains(msgId) && activityDeadline > now) {
+				updateNearest(activityDeadline);
+			}
+		}
+	}
+	if (!nearest) {
+		_timer.cancel();
+		return;
+	}
+	_timer.callOnce(std::max(nearest - now, crl::time(0)));
+}
+
+crl::time ReadMetricsTracker::activeUntil() const {
+	return _lastActivity ? (_lastActivity + kActivityTimeout) : 0;
+}
+
+void ReadMetricsTracker::addElapsed(
+		TrackedItem &tracked,
+		crl::time from,
+		crl::time till,
+		crl::time activeUntil) const {
+	if (till <= from) {
+		return;
+	}
+	tracked.totalInView += (till - from);
+	if (activeUntil > from) {
+		tracked.activeInView += std::max(std::min(till, activeUntil) - from, crl::time(0));
+		tracked.activeInView = std::min(tracked.activeInView, tracked.totalInView);
+	}
+}
+
+void ReadMetricsTracker::finalize(
+		MsgId msgId,
+		const TrackedItem &tracked) {
+	if (tracked.viewId == 0 || tracked.totalInView < kMinReportThreshold) {
+		return;
+	}
+	const auto heightRatio = (tracked.maxViewportHeight > 0)
+		? qRound((tracked.maxItemHeight * 1000.0) / tracked.maxViewportHeight)
+		: 0;
+	const auto seenRange = (tracked.maxItemHeight > 0)
+		? std::clamp(
+			qRound(((tracked.seenBottom - tracked.seenTop) * 1000.0)
+				/ tracked.maxItemHeight),
+			0,
+			1000)
+		: 0;
+	_peer->session().api().readMetrics().add(_peer, {
+		.msgId = msgId,
+		.viewId = tracked.viewId,
+		.timeInViewMs = int(tracked.totalInView),
+		.activeTimeInViewMs = int(tracked.activeInView),
+		.heightToViewportRatioPermille = heightRatio,
+		.seenRangeRatioPermille = seenRange,
+	});
+}
+
+void ReadMetricsTracker::finalizeAll() {
+	sync(crl::now());
+	for (const auto &[msgId, tracked] : _tracked) {
+		finalize(msgId, tracked);
+	}
+	_tracked.clear();
+	_timer.cancel();
+}
+
+bool ReadMetricsTracker::ShouldTrack(not_null<HistoryItem*> item) {
+	return item->isRegular() && item->hasViews();
+}
+
+} // namespace HistoryView
diff --git a/Telegram/SourceFiles/history/view/history_view_read_metrics_tracker.h b/Telegram/SourceFiles/history/view/history_view_read_metrics_tracker.h
new file mode 100644
index 0000000000..1be6087a7e
--- /dev/null
+++ b/Telegram/SourceFiles/history/view/history_view_read_metrics_tracker.h
@@ -0,0 +1,81 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+#include "base/timer.h"
+
+class PeerData;
+class HistoryItem;
+
+namespace HistoryView {
+
+class ReadMetricsTracker final {
+public:
+	explicit ReadMetricsTracker(not_null<PeerData*> peer);
+	~ReadMetricsTracker();
+
+	void startBatch(int visibleTop, int visibleBottom);
+	void push(not_null<HistoryItem*> item, int itemTop, int itemHeight);
+	void endBatch();
+	void registerActivity();
+	void setScreenActive(bool active);
+	void pauseTracking();
+	void resumeTracking();
+
+private:
+	struct TrackedItem {
+		uint64 viewId = 0;
+		crl::time entryGraceStart = 0;
+		crl::time trackingStarted = 0;
+		crl::time lastUpdate = 0;
+		crl::time totalInView = 0;
+		crl::time activeInView = 0;
+		int seenTop = std::numeric_limits<int>::max();
+		int seenBottom = 0;
+		int maxItemHeight = 0;
+		int maxViewportHeight = 0;
+		bool entryGracePending = false;
+		bool exitGracePending = false;
+		crl::time exitGraceStart = 0;
+	};
+
+	void onTimeout();
+	void sync(crl::time now);
+	void processTransitions(crl::time now, crl::time activeUntil);
+	void accumulate(crl::time now, crl::time activeUntil);
+	void refreshPaused(crl::time now);
+	void restartTimer();
+	[[nodiscard]] crl::time activeUntil() const;
+	void addElapsed(
+		TrackedItem &tracked,
+		crl::time from,
+		crl::time till,
+		crl::time activeUntil) const;
+	void finalize(MsgId msgId, const TrackedItem &tracked);
+	void finalizeAll();
+	[[nodiscard]] static bool ShouldTrack(not_null<HistoryItem*> item);
+
+	const not_null<PeerData*> _peer;
+	base::flat_map<MsgId, TrackedItem> _tracked;
+	base::flat_set<MsgId> _currentlyVisible;
+	crl::time _batchNow = 0;
+	int _batchViewportHeight = 0;
+	int _batchVisibleTop = 0;
+	int _batchVisibleBottom = 0;
+	base::flat_set<MsgId> _batchVisible;
+	crl::time _lastActivity = 0;
+	bool _appActive = true;
+	bool _screenActive = true;
+	bool _paused = false;
+	crl::time _pausedSince = 0;
+	base::Timer _timer;
+	rpl::lifetime _lifetime;
+
+};
+
+} // namespace HistoryView