CrossChat
CrossChat is a Manifest V3 browser extension that swaps YouTube’s live chat for the streamer’s Twitch chat, rendering native Twitch emotes along with 7TV, BTTV and FFZ. Reading needs no account; logging into Twitch lets you send messages too.
See ARCHITECTURE.md for the design and CLAUDE.md for a
map of the code.
Features
- Reads a Twitch channel’s chat inside YouTube, in place of the native chat.
- Renders real emotes: native Twitch plus 7TV, BTTV and FFZ, both global and per-channel.
- Reading is anonymous, no login required.
- Optional Twitch login to send messages.
- Remembers which Twitch channel maps to each YouTube channel.
- Themeable, configurable panel that survives theatre mode and in-app navigation.
Develop
npm install
npm run dev # vite dev server + HMR
npm run build # typecheck + build to dist/
npm run typecheck # typecheck only
There is no test suite or linter; tsc (strict) is the only static gate, so keep the build
clean. Verification is manual: build, load it, and exercise it on a live stream.
Releases are automated with release-please from Conventional Commits; see
RELEASING.md.
How it works
Two execution contexts talk over one typed chrome.runtime port. The content script renders the
panel and forwards what you type; it holds no sockets and no tokens. The service worker owns the
connections and your Twitch identity, running one session per panel that resolves the channel,
streams messages in through a ChatSource, composites emotes, and sends through a ChatSink
when you are logged in.
These source and sink boundaries are deliberate: adding a platform should mean a new module, not changes to the engine or panel.
Privacy
CrossChat has no backend and no analytics. It talks only to Twitch and the emote providers from
your browser. Your Twitch token, channel mappings and settings stay in chrome.storage.local on
your machine.
Contributing
Issues and pull requests are welcome. Keep the build clean and respect the source/sink boundaries above. The Twitch and emote-provider APIs change often, so verify request shapes against current docs when working on those paths.
License
MIT © Jaimy Smets