Letterpress-1

Letterpress-1 is made by The Letter Company and describes itself as a coding agent, harness and IDE for growth engineering. It works against a team's git repository, opening pull requests with live previews for landing pages, blog posts, A/B tests, and de-anonymization flows. It can be installed through an npm package and is also reachable from an app, Slack, and agents over MCP.

What It Is

Letterpress-1 is an agent for teams that manage their marketing site in git. A user asks in plain language, for example to fix the top issues on a site or add a comparison page. The agent reads the site, plans the change, builds it in a sandbox, reviews its own work, and opens a pull request with a preview link.

Build, Plan and Fix modes

The homepage describes three modes. Build creates pages and content, and is described as tuned to write brand-ready copy and keep brand visuals. Plan takes a growth goal and produces a build plan that lands directly in the repository. Fix finds broken things across a marketing site and dispatches pull requests to correct them.

Growth primitives

It ships with pre-built primitives grouped by problem. Proofs, Simulations and Benchmarks cover agentic conviction. Phantoms, Kernels and Letterbases cover GEO and SEO work such as comparison pages and deepening thin pages. Visitors and Mailers cover inbound conversion through de-anonymization and outbound sequences. The vendor says these replace tools such as G2, Trustpilot, Semrush, Sanity, Profound, RB2B and Instantly.

Surfaces and review control

Letterpress-1 is available in the Letter platform, a Slack app, a CLI, a website portal, a standalone desktop app, and through Claude Code, Codex or any MCP-capable agent. Text can be edited directly on a site or preview (⌘L) and turned into a pull request. Each change returns as a live preview, and the user chooses whether it stays a preview, becomes a pull request, or merges once checks pass. The vendor also claims it produces more tasteful changes than Codex on the same prompt.