Resend API

Modern developer-first transactional email API with React Email support, clean SDK design, and a focus on simplicity and deliverability.

Evaluated Mar 07, 2026 (0d ago) vcurrent

Homepage ↗ Repo ↗ Communication resend email transactional developer-first rest-api sdk react-email

⚙ Agent Friendliness

/ 100

Can an agent use this?

🔒 Security

/ 100

Is it safe for agents?

⚡ Reliability

/ 100

Does it work consistently?

Score Breakdown

⚙ Agent Friendliness

MCP Quality

Documentation

Error Messages

Auth Simplicity

Rate Limits

🔒 Security

TLS Enforcement

100

Auth Strength

Scope Granularity

Dep. Hygiene

Secret Handling

Simple API key auth. Domain verification required for sending. No granular scopes — API key is all-or-nothing. Young platform — security posture still maturing. SOC2 in progress.

⚡ Reliability

Uptime/SLA

Version Stability

Breaking Changes

Error Recovery

Best When

A developer-focused agent needs the simplest possible email API with clean SDKs and React Email support.

Avoid When

You need marketing campaign features, custom dedicated IPs, or very high volume sending.

Use Cases

• Sending transactional emails from agent workflows with minimal setup
• React Email template rendering and delivery
• Password reset, verification, and notification emails
• Email testing and preview in development
• Simple email automation without legacy API complexity

Not For

• Marketing bulk email at scale (SendGrid or Mailgun better)
• High-volume sending requiring custom dedicated IPs
• Teams needing advanced suppression management

Interface

REST API

Yes

GraphQL

gRPC

MCP Server

SDK

Yes

Webhooks

Yes

OpenAPI Spec ↗

Authentication

Methods: api_key

OAuth: No Scopes: No

API key in Authorization Bearer header. Keys from Resend dashboard. Very simple - perfect for agents.

Pricing

Model: freemium

Free tier: Yes

Requires CC: No

Generous free tier. No credit card required. One of the best free tiers for transactional email development.

Agent Metadata

Pagination

cursor

Idempotent

Retry Guidance

Documented

Known Gotchas

⚠ Domain verification required before sending (standard for all email APIs)
⚠ Rate limits on free tier are lower than SendGrid/Postmark
⚠ No MCP server available yet
⚠ Newer service with less battle-testing than SendGrid/Mailgun at high volumes
⚠ Batch sending API is newer and may have fewer edge cases handled

Alternatives

sendgrid-api postmark-api mailgun-api

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API endpoint ↗ Agent guide ↗ Report inaccuracy

Scores are editorial opinions as of 2026-03-07.