Compose AI vs Grammarly AI (GrammarlyGO). Side by side.

For quick email drafting in Gmail on a desktop, Compose AI's autocomplete can be faster because it learns your style. But Grammarly gives you more control—tone suggestions, rewriting, and proofreading—and works on your phone too. If you write a lot of emails on the go, Grammarly wins.

Grammarly has a mobile keyboard app for iOS and Android, so you can use it in any app. Compose AI has no mobile app—it only works as a Chrome extension on desktop. If you write on your phone, choose Grammarly.

Grammarly has a stronger privacy stance: it does not sell your data, does not train AI on your content, and offers enterprise-grade encryption. Compose AI uses your emails to learn your writing style, which means it reads and stores your email content. For sensitive work, Grammarly is safer.

Compose AI's free tier is fully functional for autocomplete and basic rewriting—no payment needed. Grammarly's free tier is good for grammar and clarity, but its generative features (rewriting, brainstorming) have monthly limits. Heavy writers will want Grammarly Premium ($12-30/month).

Both are easy. Compose AI is a one-click Chrome extension install. Grammarly requires a few more steps (download desktop app, set permissions, create a voice profile) but guides you through it. For absolute beginners, Compose AI is slightly simpler.

Grammarly has official add-ins for both Microsoft Word and Google Docs, plus a desktop app that works system-wide. Compose AI only works in the Chrome browser, so it works in Google Docs but not in Microsoft Word unless you use the web version in Chrome.