LagSync Releases

Full changelog for all public versions. New entries will be added here as releases roll out.

1.3.0

2026-08-05

Live now on Firefox. Chrome, Edge, Safari, and Brave update automatically once their store review finishes.

Permissions and privacy

  • Change: LagSync no longer asks for access to every website. It now ships with access to 19 video sites (YouTube, Netflix, Twitch, Vimeo, Disney+, Prime Video, Hulu, Max, and more), and anything else is yours to allow, one site at a time.
  • Feature: New "Site access" section in Settings. Add a site to allow it, remove it to revoke it, and see the full built-in list. There is still an "Allow on all sites" switch if you'd rather not think about it — it's off by default.
  • Feature: Open the popup on a site LagSync doesn't cover and it offers to enable that one site, then reloads the page for you. LagSync has to be in place before the video starts loading, so a reload is genuinely required.
  • Change: Removed the tabs permission. Added scripting (this is what makes per-site access possible) and activeTab (so the popup can tell you which site you're on). Neither shows an install warning.
  • Note: If you're upgrading, your existing access is kept so nothing stops working. You can narrow it whenever you like from Settings → Site access.

Playback

  • Fix: YouTube no longer freezes mid-video with a full buffer and refuses to recover until you reload the page.
  • Fix: Video quality and frame rate no longer drop on YouTube and Vimeo. LagSync was discarding buffered video to apply delay changes sooner, which those players read as a bad connection and answered by dropping resolution. It no longer does that on video-on-demand. Twitch and other live streams still trim, where it's necessary.
  • Fix (Firefox, Edge, Safari): Regular videos no longer get routed through the frame-capture path meant for live streams — on Firefox this was visibly softer and pinned YouTube playback to roughly 13 fps; it now runs at the normal ~30 fps. Live streams are unaffected; they still use frame capture, which is the only thing that works for them.
  • Fix (Firefox): Twitch live streams keep their delay. Twitch's player on Firefox reports a live stream as a finite "video" with an absurd length (about 292,000 years), which the fix above initially mistook for an ordinary video. Durations no real video can have are now treated as the live signal they are. Verified on live channels against the exact failure.
  • Improvement: When frame capture is the right path, frames are now captured at the size they're actually shown at instead of the video's full resolution, and the frame buffer has a memory ceiling. On a 4K stream this was previously hundreds of megabytes.
  • Fix: Removed a console error (chrome-extension://invalid/ net::ERR_FAILED) that appeared on every page, with the extension both on and off, and a blocking request that came with it.
  • Change: If you had set "Max buffer" to trim buffered video, this update turns it off. That setting is what caused the quality drop and part of the freeze above, so leaving it as it was would have meant installing the fix and still having the bug. It's the only setting this update changes, and you can set it back in Settings.

Performance

  • Improvement: With LagSync switched off, it now does essentially nothing. The periodic scanner, the DOM observer, and the media-pipeline hooks all stand down instead of running and returning early on every page you open.
  • Improvement: Frames with no video — ads, embeds, player chrome — no longer open a connection to the extension's background worker or run a stats timer.
  • Fix: Dragging the delay slider no longer writes to synced storage on every pixel of movement, which could exceed the browser's write quota and cause later setting changes to be silently dropped.

1.2.2

2026-05-28

Safari (macOS)

  • Feature: Netflix now works on Safari. Delay applies via the MSE path, same as Chrome.
  • Fix: Twitch delay now works on Safari, and can be changed mid-stream without reloading the tab.
  • Removed support: Prime Video is not supported on Safari. Safari runs Prime on a FairPlay-protected native HLS pipeline where none of the delay paths LagSync uses on other browsers are viable. Chrome, Edge, and Firefox are unaffected.

Donations

  • Improvement: Donation prompt is now surfaced more prominently as you accumulate usage — quieter for brand-new users, more visible after the extension has actually helped on real sessions. Tied to local usage stats; nothing about which sites you watch is sent anywhere (still 100% on-device, as before).

1.2.1

2026-04-28

Privacy

  • Feature: Added a "Turn off and pause usage stats" toggle in Settings → Privacy. Default is on. Stats are stored locally on this device only — they are never sent anywhere.
  • Feature: Turning the toggle off opens a confirmation prompt with three choices: Cancel, Pause only (keep existing stats), or Pause & delete (clear all stored stats).
  • Improvement: While paused, the Stats page hides all content and shows a "Usage stats are paused" message with a "Resume usage stats" shortcut. The background heartbeat skips recording entirely while paused, so nothing accumulates.

Edge support

  • Fix: Delay now applies on all sites in Microsoft Edge. Some Edge builds don't reliably run manifest world: "MAIN" content scripts at document_start, silently leaving the MSE/WebAudio/canvas hooks uninstalled. page_script.js is now also injected from the content script (with a double-init guard) so the hooks install on every Edge build.
  • Fix: Twitch (and other blob-backed live streams) now uses the frame-capture canvas pipeline on Edge, matching Firefox. The worker-MSE timestamp-offset path that works on Chrome did not produce a visible delay on Edge for these streams.

Sync engine and stability

  • Fix: Prime Video Instant mode now applies as a single hard jump instead of burst steps. Prime's player was rebuffering on the ramped bursts; a single jump avoids the stall while still being instant.
  • Fix: Twitch startup regression when LagSync is already enabled at page load. Worker/live-edge config is now refreshed automatically on startup, so delay applies without requiring a manual toggle.
  • Fix: Reduced startup stutter on Twitch/Edge by avoiding unnecessary WebAudio hooking in positive-delay mode.
  • Improvement: Instant increase mode uses safer near-instant burst behavior in no-trim contexts to reduce boundary-time stalls/rebuffering (except on Prime, see above).
  • Improvement: YouTube Instant mode uses near-instant burst stepping for faster feel with better stability.
  • Fix: YouTube live streams that disable seeking backward (no-DVR live) now apply delay correctly via the canvas frame-capture pipeline, since MSE timestampOffset shifts would rebuffer against the pinned live edge.

Timing and controls

  • Fix: Toggling LagSync off now shows 0 ms immediately in the popup. Previously the popup kept displaying the last-applied delay (e.g. 180 ms) until it was closed and reopened, and as a side effect the next toggle-on skipped its countdown.
  • Fix: "Starts adjusting" countdown estimation is more accurate on YouTube/VOD by limiting seekable fallback to trim-blocked contexts.
  • Fix: Speed and max-buffer settings now apply immediately on first click (no stale value delay).

Docs

  • Added: Browser differences doc covering the per-browser pipeline choices (Chrome MSE vs Edge/Firefox canvas on Twitch, Firefox/Safari/Edge injection path, etc.).
  • Added: Detailed timing/mode behavior documentation, including the Prime Video Instant exception.
  • Added: Technique and site-type behavior map (DRM/live-edge/worker/blob/iframe/etc.).

1.01

2026-04-06
  • Fix: keep Twitch/HUD visible by inserting delayed canvas sibling with z-index 0.
  • Feature: capability-based pipeline selection (MSE vs canvas) instead of host hardcoding.
  • Fix: Firefox Kick compatibility with srcObject detection and rAF + createImageBitmap fallback.
  • Fix: stabilize canvas pipeline to avoid black flashes and ensure setting changes apply reliably.
  • Improvement: generalized "twitch" naming to a generic canvas/live-edge pipeline.
  • Major Update: refactored codebase to TypeScript for stronger type-safety and reliability.
  • Feature: added compatibility for Prime Video.

1.0

2026-04-03
  • Initial release.
  • Core lag sync features via MSE.
  • Bluetooth audio delay compensation.
  • Basic audio/video offset controls.