Letter

Coding agent for SEO and AI search that opens pull requests

#1 of 97.9/10

The pick for developer-led teams: it fixes and builds on your site as reviewable pull requests and meters every action, but it is not a push-button suite.

Best for: Developer-led teams that keep their site in git and want API- and MCP-accessible, token-metered primitives.
Skip if: You want a push-button suite with a keyword and backlink database and no repository to review.

Visit Letter

Scores

AI answer visibility 25%6Measures AI answers and builds the pages that answer them, but its pricing page does not name the engines it tracks, so it sits in the middle band.
Search fundamentals 20%6Reads and fixes your site, but has no keyword or backlink index of its own.
Changes it makes 20%10Makes the change itself as a pull request with a preview, which is the highest bar here.
API and MCP access 15%10API, CLI and MCP on every plan, drawing on the same token pool.
Pricing you can check 10%9Every plan priced publicly, free tokens to start, spend cap included.
Evidence you can inspect 10%8Every change is a diff you review; every token is on a line-by-line bill.

Scored against the rubric on how we rank.

Strengths

Fixes issues and builds pages as pull requests on your own repo, each with a preview to review before merging.
API, CLI and MCP on every plan, so your own agent can drive the same work.
Measures how often AI answers name or cite you, and acts on it in the same place.
One token pool for everything, with a spend cap, alerts and a line-by-line bill.

Limits

Built for teams using git: without a repo to open pull requests on, most of its value is out of reach.
Does not sell a keyword or backlink index like Ahrefs or Semrush.
Usage-based: you estimate tokens rather than buy a fixed bundle of reports.

Pricing and access

Price (from): $25/month (Hobbyist, 2,500 tokens), up to $2,500/month (Scale)
Pricing model: Monthly token pool spent on any work; agent runs at model cost plus 20%
Free start: 1,000 free tokens to start, no card
API: Yes, every plan
MCP: Yes, every plan
AI engines: AI visibility answers metered per answer read; see its pricing page
Measures AI answers: Asks AI engines the questions your buyers ask and records whether the answer names or cites you, billed per answer read.
Improves AI answers: Builds the pages and fixes that answer those questions on your own site, as pull requests.

Sources

Pricing and plan contents (letter.dev/pricing)
Product overview (letter.dev)

Read on the review date. Plans change; the source is the final word.