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Letter
What Letter is
Letter is an email marketing automation platform for SaaS, available through its web interface and API. It supports lead capture, event-driven sequences, broadcasts, audience segmentation, and transactional email. Embeddable forms add contacts directly to Letter and include double opt-in and spam protection. A visual sequence editor lets you use event, form-submission, or list-entry triggers with branching, waits, and test sends. Broadcasts can target segments based on contact traits, events, and lists, with a live audience preview. Transactional messages can be sent through a POST /v1/send API call using existing HTML and a verified domain. Letter lists six integrations: Zapier, Facebook Lead Ads, Segment, PostHog, Make, and Tally. Developer access includes a REST API, CLI, typed SDKs, webhooks, and Node.js, Python, and Ruby examples. The free plan costs nothing, forever, for up to 1,000 contacts and 5,000 emails monthly, with unlimited events.
Who it suits
Letter suits SaaS teams that need automated email, segmentation, and transactional delivery through web or API tools. The free plan fits users starting within its contact and monthly email limits.
What it does well
- Visual editor supports branching and waits
- Forms include double opt-in and spam protection
- Unlimited events on the free plan
- REST API, SDKs, CLI, and webhooks
- Six listed native integrations
What to know first
- Free plan limited to 1,000 contacts
- Free plan capped at 5,000 emails monthly
- Free plan includes a Powered by Letter badge
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Free | Free forever · no card required · Up to 1,000 contacts · up to 5,000 emails sent/month · all features included · unlimited events tracked · includes a small “Powered by Letter” badge | Free |
As letter.app lists them, read 12 Oct 2026. The maker's own page has the final word.
Verdict
Letter combines SaaS-focused automation, segmentation, broadcasts, and transactional sending in one platform. Its free plan includes all features but sets clear contact and email limits.
Facts from Letter's own pages
- AI assistants
- Letter offers a remote MCP server for Claude, ChatGPT, and GitHub Copilot with OAuth and read-only or read-and-write access modes. · letter.app, 12 Oct 2026
- Broadcasts
- Broadcasts can target segments built from contact traits, events, and lists, with a live audience preview. · letter.app, 12 Oct 2026
- Company location
- The site footer identifies the company as Bromance Studio SRL and lists Brussels, Belgium. · letter.app, 12 Oct 2026
- Custom plans
- Letter invites users with more than 500,000 contacts or needs for custom routing, dedicated IPs, or SLAs to request custom pricing. · letter.app, 12 Oct 2026
- Data and billing limits
- Pricing is based on the number of contacts stored, with unlimited events; the free plan is limited to 5,000 emails per month. · letter.app, 12 Oct 2026
- Developer access
- Letter provides a REST API, CLI, typed SDKs, webhooks, and SDK examples for Node.js, Python, and Ruby. · letter.app, 12 Oct 2026
- Email automation
- Yes · letter.app, 20 Sept 2026
- Forms
- Embeddable forms support double opt-in and spam protection, and add contacts directly to Letter. · letter.app, 12 Oct 2026
- Free plan
- Yes · letter.app, 20 Sept 2026
- Integrations
- The integrations page lists Zapier, Facebook Lead Ads, Segment, PostHog, Make, and Tally. · letter.app, 12 Oct 2026
- Native integrations
- 6 · letter.app, 20 Sept 2026
- Paid billing
- Paid plans are billed monthly with no contract, and users can cancel anytime. · letter.app, 12 Oct 2026
- Paid trial
- Every paid plan starts with a 14-day free trial with no card up front; afterward, the account drops back to the free plan if the user does not continue. · letter.app, 12 Oct 2026
- Purpose
- Letter describes itself as an email marketing automation platform for SaaS, covering lead capture, event-driven sequences, broadcasts, and transactional email. · letter.app, 12 Oct 2026
- Audience segmentation
- Yes · letter.app, 20 Sept 2026
- Sequences
- Its visual sequence editor supports event, form-submission, and list-entry triggers, branching, waits, and test sends. · letter.app, 12 Oct 2026
- Transactional email
- Transactional email can be sent with a POST /v1/send API call using existing HTML and the same verified domain and delivery infrastructure as marketing email. · letter.app, 12 Oct 2026
Where Letter stands on Freedom251
- Email Marketing Software#44 of 187
- Email marketing tools#96 of 187