Grammarly reads every word you type. That is how it works — the browser extension intercepts your keystrokes and sends the text to Grammarly's servers for processing. This is documented in their privacy policy. Most users do not think about it.
If you are writing anything sensitive — legal documents, medical notes, confidential business content, personal correspondence — you may want an alternative that does not send your text anywhere.
How AI Writing Assistant for Firefox works differently
All text processing happens inside Firefox. When you use the extension, your text is processed by JavaScript running in the browser. Nothing is sent to an external server or API.
This is architecturally different from cloud-based grammar tools. There is no backend to receive your text. There is no company server logging what you wrote. The processing happens on your machine.
What it does
- Grammar checking: flags likely errors with suggestions
- Text rewriting: rephrase sentences for clarity
- Tone adjustment: shift text from formal to casual or vice versa
- Expansion: convert a brief note into a full paragraph
- Simplification: reduce complex text to plain language
These cover the use cases most people actually need grammar tools for.
Comparison with Grammarly
| Feature | Grammarly | AI Writing Assistant |
|---|---|---|
| Grammar check | Yes | Yes |
| Cloud processing | Yes (required) | No (local only) |
| Account required | Yes | No |
| Works offline | No | Yes |
| Privacy | Text sent to Grammarly servers | Text stays in browser |
| Cost | Free / $12+/month | Free |
The tradeoff is real: Grammarly's cloud processing likely produces better suggestions because it uses a larger model. AI Writing Assistant processes locally, which means smaller model, potentially less sophisticated suggestions. But for anyone with privacy requirements, the local option is the right tool.
Who it is for
- Journalists or researchers writing about sensitive topics
- Lawyers, doctors, therapists who work with confidential content
- Anyone who prefers not to share their writing with a third party
- People who work in environments where cloud services are restricted
Install it
AI Writing Assistant for Firefox — Firefox Add-ons
Free. No account. No cloud. Works in Firefox.
AI Writing Assistant is one of 11 Firefox extensions I built — all free, no-account, no-server. See the full series for the others.
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