BYOK Grammar Checker Chrome Extension

LexiLint is the only Chrome extension that lets you use your own AI API key for grammar checking. Your text goes directly from your browser to Google Gemini, OpenAI, or Claude — LexiLint never sees it. Gemini is free, making AI grammar checking free for most users.

🤖 New: LexiLint for AI Assistants

Use LexiLint's spell and grammar checking directly in Claude Desktop, ChatGPT, Cursor, and other AI assistants via the Model Context Protocol (MCP).

Learn More About MCP View on npm

What Does BYOK Mean?

BYOK — Bring Your Own API Key — means you control which AI provider processes your writing, and you authenticate directly with them. No middleman. No third-party server receiving your text.

Most grammar tools (including Grammarly) route your text through their own servers where it's processed, logged, and potentially used to train their models. With BYOK, the request goes: your browser → your API key → your chosen AI provider. LexiLint is just the interface.

Supported AI Providers

Google Gemini

Free tier available

Generous free tier at aistudio.google.com. No credit card required. Covers most daily writing tasks at zero cost.

OpenAI

Premium

High-accuracy grammar and style checking. Use your existing OpenAI API key.

Anthropic Claude

Premium

Strong contextual understanding for nuanced writing. Use your existing Anthropic API key.

Local LLM

Coming soon

100% offline AI grammar — no API key, no internet, no data leaving your machine at all.

How to Set Up BYOK in LexiLint

  1. 1
    Install LexiLint from the Chrome Web Store — free, no account required.
  2. 2
    Get a free Gemini API key at aistudio.google.com. No credit card needed.
  3. 3
    Open LexiLint settings — click the extension icon → Settings → paste your API key.
  4. 4
    Click "Check Grammar (AI)" on any webpage. Your text goes directly to Gemini — LexiLint never receives it.

LexiLint BYOK vs Other Grammar Checkers

Feature LexiLint (BYOK) Grammarly LanguageTool
Choose your AI provider ✓ Gemini, OpenAI, Claude ✗ Locked in ✗ Their server only
Text sent to LexiLint servers ✓ Never ✗ Always ✗ Always (cloud mode)
Free AI grammar checking ✓ Free with Gemini key ✗ Paid only ✗ Limited free tier
Works on localhost / staging ✓ Yes ✗ No ✗ No
Offline spell checking ✓ 100% offline ✗ Requires internet ✗ Requires internet
Works on any webpage ✓ Any page ✗ Limited sites ✗ Limited sites

Frequently Asked Questions

  • What does BYOK mean for a grammar checker?
    BYOK stands for Bring Your Own API Key. Instead of routing your text through LexiLint's servers, you provide your own key from an AI provider. Your text goes directly from your browser to Google Gemini, OpenAI, or Claude — LexiLint never sees it.
  • Is Gemini really free for grammar checking?
    Yes. Google Gemini has a free tier at aistudio.google.com that covers most daily writing tasks. No credit card required. For heavier usage, paid tiers are available.
  • Is my writing sent to LexiLint when I use BYOK?
    No. With BYOK your text goes directly from your browser to your chosen AI provider. LexiLint is the interface only — it never receives, stores, or processes your writing on its own servers.
  • Can I use BYOK on any website?
    Yes. LexiLint works on any webpage — including localhost, staging environments, and internal tools. Most other grammar extensions are restricted to specific sites.
  • Is local LLM support coming?
    Yes. LexiLint is working on local LLM support — 100% offline AI grammar checking with no API key and no internet connection required. The spell checker is already fully offline today.

Grammar Checking on Your Terms

Your own API key. Your chosen provider. Your text never leaves your control. Install free — spell checking works instantly, no API key needed.

Add to Chrome — Free