Resend vs Postmark vs SendGrid vs Mailgun
Four transactional-email providers with very different free tiers — the developer-first React Email API, the high-deliverability specialist, the battle-tested at-scale SMTP relay, and the API-first routing + validation engine — compared on free volume, deliverability, and pricing.
| Resend | Postmark | SendGrid | Mailgun | |
|---|---|---|---|---|
| Free tier note | Developer-first transactional email with React Email templates and a clean API — 3,000 emails/month (100/day) free forever with 1 custom domain and full DKIM/SPF setup. | High-deliverability transactional email — 100 emails/month free forever after a 30-day trial, with separate transactional + broadcast streams and SMTP relay + API. | Twilio SendGrid — 100 emails/day (3,000/month) free forever with SMTP relay + API, plus marketing-campaign tools on paid plans. Battle-tested at scale. | Mailgun — 5,000 emails/month free for the first 3 months, then pay-as-you-go (no forever-free tier). Robust REST API, inbound routing, and email validation. |
| Bandwidth | n/a | n/a | n/a | n/a |
| Builds | n/a | n/a | n/a | n/a |
| Requests | 3,000 emails/month (100/day), 1 custom domain | 100 emails/month free forever (after 30-day trial) | 100 emails/day (3,000/month) free forever | 5,000 emails/month free for first 3 months, then pay-as-you-go |
| Custom domains | 1 | n/a | n/a | n/a |
| Paid from | $20/mo | $15/mo | $20/mo | $15/mo |
| Generosity ★ | 12 | 4 | 4 | 4 |
| Last verified | 2025-09-01 | 2025-09-01 | 2025-09-01 | 2025-09-01 |
| Visit site | Resend ↗ | Postmark ↗ | SendGrid ↗ | Mailgun ↗ |
Data verified 2025-09-01.