# Resend

> Email API for sending transactional and marketing email, with SDKs, SMTP relay, inbound email and webhooks.

- Category: [Transactional email](https://freetier.tech/c/email.md)
- Free tier: Always free. 3,000 transactional emails per month, capped at 100 per day, with up to 3 verified domains.
- Commercial use not stated
- No card required
- Pricing: https://resend.com/pricing
- Last verified: 2026-10-28

## Free tier limits

- 3,000 transactional emails per month
- 100 emails per day (UTC calendar day)
- 3 verified domains
- 1 webhook endpoint
- 30-day data retention
- 1,000 marketing contacts
- 10 API requests per second per team

## Gotchas

- Received (inbound) emails and every To, CC and BCC recipient count against the daily and monthly quota.
- Until a domain is verified you can only send test emails from onboarding@resend.dev to your own account address; other recipients get a 403.
- API keys with "Sending access" can only send email; creating and verifying domains needs a "Full access" key.
- Going over the quota returns a 429 (daily_quota_exceeded or monthly_quota_exceeded); the daily quota resets at midnight UTC.
- A domain's region and return path can't be changed after it is created.

## Setup

### What the human does

1. Sign up at https://resend.com/signup (Google, GitHub or email).
2. Create an API key at https://resend.com/api-keys (Full access if the agent will set up domains), or approve the MCP server's OAuth login.
3. Add the DNS records Resend lists for your sending domain at your DNS provider, unless the agent can edit DNS.

### How the agent gets access

#### API key

- Install: `npm install -g resend-cli`
- Get it at: https://resend.com/api-keys
- Env var: `RESEND_API_KEY`
- Notes: The Resend CLI and local MCP server read RESEND_API_KEY; `resend login` stores a pasted key instead. The key is shown only once.

#### OAuth

- Run: `claude plugin install resend@claude-plugins-official`
- Notes: Adds the hosted MCP server (https://mcp.resend.com/mcp); run /mcp and log in through the browser. For Codex, `codex mcp add resend --url https://mcp.resend.com/mcp`.

### Verify

```sh
resend doctor
```

## Docs

- Quickstart: https://resend.com/docs/introduction
- llms.txt: https://resend.com/llms.txt

## Sources

- https://resend.com/pricing
- https://resend.com/pricing.md
- https://resend.com/docs/knowledge-base/account-quotas-and-limits
- https://resend.com/docs/api-reference/rate-limit
- https://resend.com/changelog/three-domains-on-the-free-tier
- https://resend.com/legal/terms-of-service
- https://resend.com/docs/knowledge-base/403-error-resend-dev-domain
- https://resend.com/docs/create-an-api-key
- https://resend.com/docs/dashboard/api-keys/introduction
- https://resend.com/docs/cli
- https://resend.com/docs/mcp-server
- https://resend.com/docs/ai-onboarding
- https://resend.com/setup.md
- https://resend.com/auth.md
- https://resend.com/signup
- https://resend.com/docs/introduction
- https://resend.com/llms.txt

JSON: https://freetier.tech/api/v1/services/resend.json