Kick Chat Translator от Pkkls

On-device first — uses Chrome's built-in Translator API (Chromium ≥138): unlimited, instant, fully local, nothing leaves your machine. One-time model download per language (one click).
Cloud fallback — for browsers without the on-device API (e.g. Brave) or language pairs not downloaded: DeepL (bring your own free key), Google, MyMemory, Lingva. Tried in order with automatic failover.
Built for busy chat — request coalescing + batching, an LRU + IndexedDB cache, and a per-channel rate budget keep it fast and gentle on providers.

Firefox / AMO notes
The Firefox build sets browser_specific_settings.gecko.id = kick-translator@pkkls.dev and strict_min_version = 121.0 (the version that supports ES-module background scripts + storage.session). Data collection: none — declare it in the AMO submission form (the manifest data_collection_permissions field would force strict_min_version 140+). web-ext lint → 0 errors.
Ignores noise — emotes, emoji spam, laughter (kkkk/jaja/lol), and streaming slang are skipped, so you only translate real messages.
Quiet by default — auto-pauses in background tabs so it never works (or spends your DeepL quota) when you're not watching.
No account, no tracking, no telemetry. Open-source (MIT).