Proofpad — AI Writing Assistant

Free grammar, spelling and style checks on any site, done locally. Add a Google AI key to unlock AI rewrites too.

v 1.3.1 The biggest change: Proofpad now checks your spelling, grammar, punctuation and style for free, right on your computer. No API key needed for that anymore. The key is now optional, and it only unlocks the AI tools: rewriting a sentence, making something shorter or longer, changing the tone, and fixing everything at once. This also fixes the credit problem you noticed. Clicking into a text box used to spend a request immediately, even before you typed anything. That's gone. The free checks never touch the API. Some suggestions now show more than one fix to pick from, instead of just one guess. There's a new button called Improve sentence. Put your cursor in a sentence, or select one, and it rewrites the whole thing for clarity and flow. This needs a key, since it's AI-driven. For fun, there's a small rewards system now. You earn levels and badges as you fix things and use Proofpad daily. You can see your progress in the popup, and a small notification appears on the page when you unlock something. Also fixed: the fonts in the popup, settings, and suggestion cards were falling back to a plain default font in some cases. Everything now uses the correct Proofpad typeface. ━━━ v 1.2 full brand refresh, fixed context-invalidation error class ━━━ Proofpad checks your writing wherever you type — email, docs, forms, comment boxes, chat — and shows what to fix, right in the field. ━━━ WHAT YOU NEED FIRST ━━━ Proofpad has no subscription and no account. It runs on your own Google AI Studio API key, which is free to create and takes about a minute: Install Proofpad. The settings page opens automatically. Get a free key at https://aistudio.google.com/apikey Paste it in and click "Test key". Until you add a key, Proofpad stays completely dormant — no underlines, no network requests, nothing. ━━━ WHAT IT DOES ━━━ Coloured wavy underlines appear under anything worth changing. Hover one to see what's wrong and why, then click Accept to apply the fix. • Correctness — spelling, grammar, punctuation, agreement, typos • Clarity — wordiness, redundancy, passive voice, tangled sentences • Engagement — bland or repetitive word choice, weak verbs • Delivery — tone, formality, hedging, inclusive phrasing Select any sentence for a rewrite: Rephrase, Shorten, Expand, More formal, More casual, Simplify, or Fix all errors. You see the options before anything is replaced. Works in plain text boxes and in rich editors, so it covers your inbox, docs, forms, comment boxes, chat, and most of the web. ━━━ BUILT TO BE CHEAP ━━━ You pay Google directly for what you use, and Proofpad works hard to keep that near zero: • Only paragraphs you actually changed get re-checked • Results are cached, so retyping something costs nothing • Typing is debounced and in-flight requests are cancelled • Requests are batched, and rate-limited to stay inside the free tier • Reasoning tokens are switched off — they bill at output rates and add nothing to proofreading Google's free tier covers 30 requests a minute and 1,500 a day. Most people will never pay anything. A live cost meter in Settings shows exactly what you've spent. ━━━ YOUR TEXT AND YOUR KEY ━━━ No account, no telemetry, no analytics, no third-party servers. Your text goes from your browser to Google's API and back — nowhere else. Proofpad refuses to read password fields, credit-card and one-time-code inputs, anything whose name looks like a secret, search boxes, read-only fields, code editors, and any field a site marks as opted out. Their contents are never transmitted. Your API key is stored on your own machine and is deliberately kept out of Chrome sync, so it never leaves the computer you typed it into. ━━━ CONTROLS ━━━ • Turn it off globally or per site • Four English dialects (US / UK / AU / CA) • Toggle each suggestion category • Sensitivity slider • Writing goals: audience, formality, domain, intent • Custom dictionary for names and jargon • Keyboard shortcuts: Alt+Shift+A accept, Alt+Shift+D dismiss ━━━ KNOWN LIMITS ━━━ • Google Docs is not supported. Docs draws its text onto a canvas, so there is no text for any extension to read. It's disabled there by default. • No plagiarism checking. That needs a licensed corpus this doesn't have. • Requires Chrome 120 or later. Proofpad is for use with Google Gemini™. Google and Gemini are trademarks of Google LLC. Proofpad is not affiliated with or endorsed by Google.