Quick answer
Resend - Resend wins for most builders who want a general-purpose email API, while AgentMail wins if you specifically need multiple inboxes and agent-style inbox management on a tighter free-tier workflow.
How the free tiers compare
The two free tiers look similar at first because both allow 3,000 emails per month, but they are shaped for different jobs. AgentMail is centered on managing inboxes for AI agents: the free plan gives 3 inboxes, 3 inbox pods, 2 webhooks, and 2 team members, so it is better when you care about programmatic inbox infrastructure more than broad email sending features. Resend is the more conventional developer email platform: it includes sending and receiving, REST and SMTP access, SDKs, scheduled and batch sending, tracking, React Email, 1 custom domain, and 30 days of retention. The tradeoff is that Resend’s free tier has a daily sending cap and requires a card, while AgentMail is card-free but narrower. Once you outgrow free, AgentMail jumps to a flat $20 plan, while Resend starts at $20 but adds usage-based overages and a more tiered path upward.
AgentMail vs Resend free tier, side by side
| AgentMailFTV 47 | ResendFTV 30 | |
|---|---|---|
| Free emails per monthResend also has a 100 emails/day limit on free. | 3,000 | 3,000 |
| Free inboxes / domainsDifferent resource types, so this is not a like-for-like quota. | 3 inboxes | 1 custom domain |
| Free storage / retentionAgentMail measures storage; Resend measures retention time. | 3 GB storage | 30 days of data retention |
| Free team / collaborationResend free includes ticket support, but no team-member quota was provided. | 2 team members | Not listed |
| Free webhook endpointsResend includes all webhook events on that one endpoint. | 2 webhook endpoints | 1 webhook endpoint |
| Free automation runs / AI creditsThese are free-tier extras on Resend only. | Not listed | 10,000 automation runs; 5 AI credits/month |
After you outgrow the free tier
AgentMail is simpler after free: the first paid tier is a flat $20/month Developer plan, then a flat $200/month Startup plan, with Enterprise as custom pricing. Resend’s paid path starts at $20/month too, but the pricing is usage-based on top of included quotas: Pro includes 50,000 emails/month and charges $0.90 per 1,000 extra emails, while Scale is $90/month with larger included limits and the same overage rate. For small teams that stay near the included limits, both start at $20, but Resend is more elastic if email volume grows unevenly. AgentMail becomes the better known-cost option once you need a bigger fixed bundle of inboxes and emails.
Cost at real usage
| Usage | AgentMail | Resend |
|---|---|---|
| 50,000 emails/moAgentMail Developer includes 10,000 emails/month, so 50,000 would require a higher plan, but no explicit overage rate was provided. Resend Pro includes 50,000 emails/month. | ~$20/mo | $20/mo |
| 100,000 emails/moAgentMail Startup includes 150,000 emails/month. Resend Scale includes 100,000 emails/month. | ~$200/mo | $90/mo |
| 150,000 emails/moResend Scale includes 100,000 emails/month and charges $0.90 per 1,000 extra emails, so 50,000 overage is about $45 on top of $90, totaling about $135; however, since no monthly cap overage formula beyond that was provided, this is only a direct arithmetic estimate from the stated rate. | $200/mo | ~$180/mo |
Estimates, not quotes. Usage-based rates change - verify with the vendor's pricing page before committing.
When to pick each one
Pick AgentMail when…
- You need several programmatically managed inboxes for agents, tests, or workflows, not just one sender domain.
- You want a free tier with no credit card required.
- You care more about inbox count, inbox pods, and webhook endpoints than about marketing-email features.
- You expect to stay under 3 inboxes and 3,000 emails/month and want to avoid paying until the workflow proves itself.
Pick Resend when…
- You need a general developer email platform for transactional or marketing mail.
- You want sending and receiving plus SMTP, REST, SDKs, scheduled emails, batch sending, and tracking in the free tier.
- You only need one custom domain and can live with a 100 emails/day cap on free.
- You want a path that starts at $20/mo and scales with extra-email usage instead of jumping straight to a bigger flat bundle.
Bottom line
For the most common builder use case, Resend is the safer default: it is a fuller email platform out of the box, and its pricing path is easier to grow into if you start small and then scale. AgentMail is the better fit when the product is really about managed inboxes for agents or workflow automation, especially if avoiding a credit card on the free tier matters. If you mainly need to send email from an app, Resend wins. If you need inbox infrastructure, AgentMail is the cleaner choice.
Read the full listings: AgentMail and Resend. Scores use the FTV methodology at /ftv. Browse more head-to-heads on /compare, or see the top-ranked free tiers on /top.