Browser extension that turns the web into an AI language tutor

What it does

Read Frog is a browser extension that overlays AI-powered translation, explanation, and text-to-speech onto any webpage or YouTube video. It can display bilingual text side-by-side or replace the original entirely, and it feeds the page title and a concise Markdown version of the full content to the AI so translations respect context rather than treating each sentence in isolation. The extension also bundles free Edge TTS voices and supports over 20 LLM providers via the Vercel AI SDK.

The interesting bit

The extension batches multiple translation requests into single API calls, claiming up to 70% cost savings, and falls back to individual requests with exponential backoff if the batch fails. That turns the usual “translate this paragraph” firehose into something closer to a managed data pipeline running inside your browser.

Key highlights

• Context-aware translation feeds the AI a Markdown digest of the entire page, not just the current sentence.
• Supports 20+ AI providers (OpenAI, DeepSeek, Claude, Gemini, Grok, Ollama, etc.) through the Vercel AI SDK, plus free Google, Microsoft, and DeepLX backends.
• Bilingual and translation-only modes that auto-retranslate visible content when you switch without refreshing.
• Selection toolbar offers real-time translation, level-tailored explanation, and Edge TTS playback with 150+ voices across 80+ languages.
• YouTube subtitle translation baked directly into the video player.
• Intelligent request batching with retry logic and automatic fallback to cut API overhead.

Caveats

• The project is under active development and the README explicitly welcomes issue reports, so expect rough edges.
• Dual-licensed under GPLv3 and a commercial license, which means closed-source forks require negotiating a license grant.

Verdict

Built for language learners who want AI nuance baked into every webpage and YouTube video; developers hunting for a lightweight translation library should look elsewhere, because this is a full browser extension with its own UI and batching engine.