Postmark vs Brevo (Sendinblue)
A detailed comparison of Postmark and Brevo (Sendinblue) for sending transactional emails. Which email API is right for your application?
Overview
Both Postmark and Brevo (Sendinblue) provide email APIs for sending transactional emails from applications. Postmark and Brevo (Sendinblue) each have strengths — Postmark is known for its developer experience, while Brevo (Sendinblue) offers different pricing and feature trade-offs. AISend is a third option worth weighing: a Resend-compatible API at lower flat pricing.
Features comparison
Key differences between Postmark and Brevo (Sendinblue): API design and developer experience, custom domain support, webhook event tracking, bounce/complaint handling, and pricing structure. Both providers offer REST APIs and SDKs but differ on pricing and migration effort. AISend is a third option — a Resend-compatible API with flat pricing and an MCP server for AI-agent senders.
Pricing
Pricing is a major factor when choosing an email API. Compare the free tiers, per-email costs at different volumes, and what's included in each plan. AISend offers 3,000 emails/month free with no credit card. Pro is $14/month for 50,000 emails — the same volume Resend charges $20/month for. Both Postmark and Brevo (Sendinblue) have transparent pricing. AISend's plans are flat with no hidden per-contact fees, and migration from a Resend-compatible API is a one-line change.
Which should you choose?
If you're choosing between Postmark and Brevo (Sendinblue), it's worth also evaluating AISend — a Resend-compatible API at lower flat pricing, with automatic bounce/complaint suppression and an MCP server for AI agents that makes switching low-risk.