Resend
The email API for developers — transactional and marketing at scale, with React Email, official SDKs, a CLI and an MCP server.
Resend is the email API for developers — a modern, developer-first alternative to the traditional ESPs. It owns the mail my app has to send: receipts, password resets, magic links, notifications. The DX is the whole point, and it's built by the same team behind React Email.
What makes it my transactional default
- A clean, modern API — a RESTful API plus SMTP relay, documented with an OpenAPI 3.0 spec, with official SDKs for Node.js, Python, PHP, Ruby, Go, Java, Rust, .NET and Laravel.
- React Email — compose emails as React components and render them to HTML. Because this project already builds UI in React, the mental model carries straight over.
- Built for agents and terminals — there's a CLI for terminal-based sending and an MCP server so agents (Claude, Cursor) can drive it directly.
- The essentials in the box — inbound email, batch sending, and open/link tracking across all plans.
Pricing model
Resend prices transactional and marketing email separately — transactional by monthly send volume, marketing by contact count. Figures below are the tier shape; check the pricing page for exact current numbers.
Transactional (by emails/month)
- Free — $0, ~3,000 emails/month (100/day), 1 domain, 30-day retention.
- Pro — from ~$20/mo, 50,000+ emails/month, up to 10 domains, no daily limit.
- Scale — from ~$90/mo, 100,000+ emails/month, dedicated IP available as an add-on.
- Enterprise — custom, 3M+ emails/month, SLA and priority support.
Marketing (by contacts)
- Free — $0, up to 1,000 contacts.
- Pro — from ~$40/mo, 5,000+ contacts.
- Enterprise — custom.
→ Resend pricing · Docs · resend.com
Why it's my transactional pick: React Email means I write system mail the same way I write UI, the SDK/CLI/MCP surface makes it trivial to send from code or an agent, and a free tier covers most side projects. I pair it with Loops for marketing and lifecycle.