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Compose AI vs Letty

Two fact sheets from our own research, side by side — pricing, platforms, API access and status re-checked by us rather than quoted from the vendors. Letty publishes a starting price ($9); Compose AI does not. Both have a free tier.

Compose AIFree Chrome extension that autocompletes sentences and email replies as you type across the webLettyGmail-only Chrome extension that drafts replies in your writing style and can be trained on your documents.

Side by side

FactCompose AILetty
CategoryAI Writing AssistantsEmail Writing
Pricing modelFreemiumFreemium
Starts at—$9 month
Public APINoNo
PlatformsChrome ExtChrome Ext
CompanyCompose AI, Inc.—
Launched2021—
Last verifiedSep 6, 2026Sep 1, 2026

What our research says

Compose AI

A low-friction way to speed up routine email and doc writing, since the free tier installs in a minute and completes sentences anywhere in Chrome. The catch is stagnation risk: the site's own copyright is frozen at 2024 and browser-native AI features increasingly do the same job for nothing.

Pros

  • Basic extension is free with no time limit
  • Autocomplete works across most web text fields, not one app
  • Learns personal writing style for suggestions

Cons

  • Chrome-only, with no API or desktop apps
  • Official pricing was unreadable in this check, an odd sign for a paid product
  • Site freshness signals suggest limited ongoing development

Letty

Letty drafts Gmail replies that match your tone and can be grounded in documents or sites you feed it, which makes it useful if most of your email already lives in Gmail. It doesn't help outside Gmail yet, and the free tier's 10 credits a month will run out fast for anyone emailing daily.

Pros

  • Generates contextual reply suggestions instead of generic templates
  • Can be trained on specific documents or websites for grounded answers
  • Three clear pricing tiers from free up to unlimited credits

Cons

  • Only works inside Gmail in Chrome; Outlook and Zoho are listed as planned but not shipped
  • Free tier's 10 monthly credits cover only light use

Which one fits

Choose Compose AI if you need

  • Heavy email writers who churn out routine replies in Gmail
  • Non-native English speakers who want inline phrasing help
  • Anyone testing writing autocomplete without paying

Choose Letty if you need

  • Gmail-heavy users who want drafted replies rather than typing every response
  • People who repeatedly reference the same documents or product pages in email

More comparisons

All Compose AI alternatives →All Letty alternatives →Browse all AI Writing Assistants →