Comment Vibe reads the tone of your comment as you type — on LinkedIn, X, YouTube, Reddit, anywhere — and flags it right next to the box. Harsh or toxic? You get a kinder rewrite in one click.
no account · no cloud · your comments never leave the browser
↑ simulated preview — the installed extension runs real on-device AI (Gemini Nano / Firefox AI runtime)
Works on any site with a comment field — social networks, forums, docs, review forms. No setup per site.
A small badge appears while you type: 😊 positive, 😐 neutral, 😕 negative or 🚫 toxic — with a one-line why.
Sounds harsher than you meant? Click the badge and copy a kinder rewrite that keeps your point.
“Great write-up, thanks for sharing! The section on caching finally made it click for me.”
“The update ships on Tuesday. Release notes are linked in the docs.”
“This is a terrible idea and it will never work in practice.”
“Only an idiot would post something like this. Delete your account.”
By default every analysis runs locally — Chrome's built-in Gemini Nano model, or Firefox's on-device AI runtime. There is no server, no account, no analytics, and it keeps working offline once the model is downloaded. The code is open source (MIT).
Optional Fast mode, off unless you turn it on, sends only the text being checked to a SubQ or TypeSafe decision model with your own API key. Writing actions stay on your device.
Uninstall survey. After uninstalling, your browser opens an optional Google Form. The extension sends no data with it, and the link has no identifiers. Answers are anonymous and covered by Google's Privacy Policy. This is separate from on-device processing and optional Fast mode.
Chrome uses the Prompt API (Gemini Nano) — a generative model, so you get rewrites, streaming and translation. Firefox's brand-new WebExtensions AI API exposes on-device classifiers, so the Firefox build focuses on the tone badge. Comment Vibe is one of the first extensions shipping on both. Microsoft Edge runs the Chrome build — on-device with Edge's built-in model after enabling the Prompt API preview in edge://flags on supported PCs, or with Fast mode.
| Feature | Chrome 138+ | Firefox 134+ |
|---|---|---|
| Tone badge (positive / neutral / negative / toxic) | ✓ | ✓ |
| “Why” explanation | ✓ model-written | ✓ classifier + confidence |
| Optional Fast mode (cloud, SubQ or TypeSafe) | ✓ | ✓ |
| Kinder rewrite suggestion | ✓ | — |
| Streaming (badge colors in early) | ✓ | — |
| Understands non-English comments | ✓ | ✓ ~100 languages |
| Output in your comment's language | ✓ | — (English) |
| Runs on-device by default | ✓ | ✓ |
Not by default. Analysis happens inside your browser using its built-in on-device model. There is no backend, no telemetry, and the extension keeps working offline once the model is downloaded. You can audit the code — it ships as raw, unminified JavaScript.
The only exception is the optional Fast mode: if you turn it on and paste your own SubQ or TypeSafe API key, the text being checked is sent to that provider's decision model for a sub-second tone check. Rewrites still run on your device, and you can switch it off at any time.
Chrome 138+ on desktop and hardware eligible for Gemini Nano. Chrome downloads the model automatically the first time it's used — no flags needed on current versions.
Firefox 134+ on desktop. Click “Enable on-device AI” in the extension popup — a multilingual classifier model (~340 MB) downloads once. On Firefox 134–139 you may also need to set browser.ml.enable and extensions.ml.enabled to true in about:config; from Firefox 140 they're on by default.
Yes — Edge runs the Chrome build. Edge's on-device model is a preview today: enable Prompt API for on-device language model in edge://flags (officially on Dev/Canary; the flag is also present on Stable) and restart — verified end-to-end on Edge Dev 157 with rewrites included. On a supported device (Windows 10/11 or macOS 13.3+, 5.5 GB VRAM, 20 GB free disk) Comment Vibe then runs fully on-device. On devices Edge doesn't support, or where an organization turned it off, use Fast mode in the popup with your SubQ or TypeSafe key. The Edge Add-ons listing is in review; until then, install from the Chrome Web Store (Edge offers “Allow extensions from other stores”).
It's not a lesser effort — it's a different engine. Chrome ships Gemini Nano, a small generative LLM that extensions can prompt, so it can write things: explanations, kinder rewrites, translations. Firefox's WebExtensions AI API (browser.trial.ml) instead exposes on-device classification models — they can judge tone (in ~100 languages) but can't write text. Same badge, different brains. When Firefox's generative backend matures for extensions, the rewrites follow.
Yes — free and open source under the MIT license. No paid tier, because there's no server to pay for.