OpenLingo

Bilingual reading & subtitles for the open web.

Original on top, translation underneath — for webpages and YouTube. Bring your own provider. No subscription.

English · 中文

---

What it does

• One-click bilingual webpages. Click the toolbar icon, every paragraph gets a translation line right below it; the original stays untouched.
• YouTube bilingual subtitles. Auto-engages when you turn on YouTube's CC. If a video has no caption track, Chrome 116+ can optionally transcribe its audio live with ElevenLabs Scribe using your own API key.
• Bring your own translator. Pick from:
  • Google (free) — works out of the box, no key needed.
  • DeepL — paste your :fx (Free) or Pro key for higher quality.
  • OpenAI-compatible — point it at GPT-4o-mini, Claude via proxy, Groq, DeepSeek, local Ollama, whatever speaks the OpenAI Chat Completions API.
• Streaming translation. What's on screen translates first; the rest streams in as you scroll.
• Local cache. Translated once, free forever — survives reloads and SPA route changes.
• Restore in one click. Toggle off and the page is back to the way you found it.

YouTube features

When you open a YouTube video with captions enabled, OpenLingo adds a small button into the player's right controls (next to the CC button). Click it to get a menu showing:

• The active caption source (USING AI CAPTIONS for YouTube's auto-generated track, USING HUMAN CAPTIONS for an authored track).
• A toggle for bilingual subtitles on this video.
• Hide this button for the rest of the video.
• Download .srt — exports the original + translated cues as a standard SubRip file.
• Caption settings… — opens the Options page.

If CC is off, the menu shows a one-click "Turn on CC" prompt that flips YouTube's own captions on.

When no YouTube caption track is available, open the toolbar popup and click Start live transcription. The original transcript appears immediately, with the translation underneath as it arrives. This fallback is currently Chromium-only.

Install

1. Grab dist.zip from a release (or build it yourself — see below) and unzip.
2. Open Chrome → chrome://extensions.
3. Enable Developer mode (top right).
4. Click Load unpacked and pick the unzipped dist/ folder.

Firefox: use dist-firefox.zip, then Load Temporary Add-on at about:debugging.

Set up

1. Click the OpenLingo toolbar icon → Open Options (or right-click the icon → Options).
2. Pick a provider:
   • Google (free) needs no setup.
   • DeepL: paste your key from deepl.com/pro-api (:fx ending = Free tier).
   • OpenAI-compatible: paste a base URL (e.g. https://api.openai.com/v1), API key, and model name.
3. Choose your target language (default: Chinese).
4. (Optional) In Bilingual video subtitles, pick a subtitle style and font size — S / M / L / XL on top of YouTube's own scaling.
5. (Optional) For videos without captions, enable Live transcription fallback, add an ElevenLabs API key, and choose automatic or fixed source-language detection.

Keys and settings live in chrome.storage.sync, so they survive reinstalls and updates. If you're signed into your browser, the browser syncs them across your devices along with your other extension data; otherwise they stay on this machine. Translation keys are sent only to their configured translation provider. The ElevenLabs key is exchanged for a short-lived transcription token when the popup detects a captionless YouTube video; audio is only captured and sent after you explicitly click Start.

Use it

• A webpage: click the toolbar icon → Translate this page. Click again to Restore.
• A YouTube video: turn on YouTube's CC. OpenLingo's button lights up and bilingual subtitles appear in a few seconds.
• A YouTube video without captions: click the toolbar icon → Start live transcription.

FAQ

Why are some places not translated? Code blocks, <pre> content, pure numbers, and paragraphs already in the target language are skipped on purpose.

Why does the YouTube button do nothing? YouTube only emits the caption track URL after CC is enabled in the player. Use the button's menu — it has a "Turn on CC" shortcut.

DeepL says 456 / quota exceeded? You're out of monthly characters. Rotate to another key, switch provider, or wait for the next reset. Cached translations keep displaying.

Does it phone home? No telemetry. Text is sent only to the translation provider you've configured. If you explicitly start live transcription, the current tab's audio is streamed to ElevenLabs until you stop it, leave the video, or a native caption track becomes available.

Build it yourself

pnpm install
pnpm build           # → dist/ (Chromium)
pnpm build:firefox   # → dist/ (Firefox)
pnpm zip             # → dist.zip

Requires Node 22+ and pnpm 10+.

License

MIT.