Get Started

ReactionSync is a Chrome extension for your computer that plays a reaction video in sync with your own copy of the show or film, each in its own tab. Setting it up takes about a minute.

Add to Chrome

One click from the Chrome Web Store. It updates itself.

Works on a computer, in Chrome and other Chromium-based browsers; phones and tablets can't run extensions. We don't support Firefox or Safari right now. Prefer to get new versions the day they ship? Install manually.

Your first pairing

The easiest way to start is with a sync link — someone has already lined the two videos up, so there's nothing to set up yourself.

First, pin it and sign in (once).
After adding it, click the puzzle-piece icon in Chrome's toolbar and pin ReactionSync, so it's one click away. Click its icon and choose Sign in with Google. Google's window shows a supabase.co address: that's our sign-in service, and we receive only your name, email address and picture (why we ask). When Google's window closes, click the ReactionSync icon again to carry on. After that it remembers you.

  1. Open the sync link that came with the reaction. Its page has a button for the reaction and one for the original: open both.
  2. Put the two side by side and press play on both. Drag one tab out into its own window and place the two windows left and right; a video in a tab hidden behind another may not be found. If either tab was open before you installed ReactionSync, reload it first.
  3. Copy the sync link. Back on its page, click Copy sync link. Do this before opening the extension, because the extension's window closes when you click anywhere else.
  4. Pick your two tabs. Click the ReactionSync icon, choose the show under 1. Source and the reaction under 2. Reaction, and click Continue. If a video isn't in the list, the FAQ explains why.
  5. Load the link. Click Load from Link, paste, and click the arrow. Both videos go to the start and play together. There's nothing to mark: the alignment comes from the link.
  6. Watch. Pause, seek or rewind on either video and the other follows. When the reactor stops the show to talk, your episode waits for them.

No sync link for what you're watching? You can line the two up yourself and save it as one — the FAQ shows how, along with anything else about using the extension.

Did your first sync work? Tell us in a minute, worked or not. If it didn't, say which two sites you were pairing.

Install manually instead (new versions sooner)

A store update takes a day or two to reach everyone after we publish it. Installing from the zip gets you the new build the moment it's out, and you update whenever you choose. It's the same extension and the same account either way.

Download...

Build ... · released ...

  1. Extract the zip to a folder you'll keep. Not your Downloads folder — see the note below.
  2. Open a new tab and go to chrome://extensions.
  3. Turn on Developer mode with the toggle in the top-right corner.
  4. Click Load unpacked and choose the folder you extracted.
  5. ReactionSync appears in the list. Click the puzzle-piece icon in your toolbar and pin it, so it's one click away.

About the warning you see when you enable Developer mode.
It is a real security mechanism: Developer mode lets you load any extension from any folder, so Chrome tells you so. We are a registered company — Dwarka Point Technologies Private Ltd — with a published privacy policy. Chrome will also show you exactly what this extension can reach: click Details on the ReactionSync card and read Site access. It lists the video sites we sync and nothing else.

Keep the folder where it is.
Chrome loads the extension from that folder every time it starts — it doesn't copy it anywhere. If you move the folder, rename it, or delete it while tidying up your Downloads, the extension stops working. Put it somewhere you won't touch by accident, like a folder in your Documents.

Installation on other Chromium-based browsers

Edge, Brave, Opera, Vivaldi and Arc all run Chrome extensions, and ReactionSync works the same way on them. The Add to Chrome button above works in these browsers too — Edge asks once whether to allow extensions from other stores; say yes.

If you're installing manually, the steps are identical — only the address of the extensions page differs.

edge://extensions

The Developer mode toggle sits in a different corner depending on the browser, but it's on that same page.

We develop and test on Chrome. These browsers share the same extension engine, so things generally behave identically — but if you hit something odd, tell us and mention which browser.

Firefox, Safari and other non-Chromium browsers

Not supported at the moment. Both use a different extension system, so it's a real piece of work rather than a repackage — we'll do it if enough people ask. If you're on one of them, let us know and we'll count you.

Updating the extension

Installed from the Chrome Web Store? Updates arrive on their own — there's nothing to do. The popup may mention a new version a day or two before the store delivers it; you can ignore that.

Installed manually? When a new version is out, the extension tells you inside the popup. Then:

  1. Download the new zip from this page.
  2. Extract it over the same folder, replacing the old files.
  3. Go to chrome://extensions and click the reload icon on the ReactionSync card.

Replacing the folder in place matters — if you remove the extension and add it back instead, you'll be signed out and have to sign in again.