Resend
Resend · Writing · Coding
Resend is an email API built for developers who need to send transactional and marketing messages without wrestling with mail server setup. It handles the messy parts of email delivery, like domain authentication and inbox placement, so you can focus on your application. The platform pairs a clean HTTP API and SDKs with React Email, a component library for building modern templates. If your product sends welcome emails, password resets, receipts, or newsletters, Resend is one of the fastest ways to get those messages out reliably.
About Resend
What Is Resend
Resend is a cloud email sending platform aimed at developers and product teams. Instead of maintaining your own SMTP server, you call an API with an API key and Resend takes care of delivery, retries, and reputation management. The company started with an open source project in 2022 and launched the full platform in 2023 after joining Y Combinator's winter batch. It's run by Zeno Rocha, who has spent years working on developer tooling. He knows this space well.
The core problem Resend solves is deliverability. Getting email into the inbox rather than the spam folder is the hardest part of sending mail, and most of the friction comes down to DNS records: SPF, DKIM, and DMARC. Resend walks you through verifying a domain and adding those records, then sends from that verified domain so your messages carry your brand instead of a generic address. No server to babysit.
One thing to be clear about: Resend isn't a replacement for Gmail or a corporate inbox. It doesn't let your team read and manage everyday mail. What it does is send and receive application email programmatically. If you want a personal mailbox on your own domain, this isn't that tool. Simple as that.
Getting Started
- Create a Resend account with your email address or GitHub, then confirm the signup from the verification message.
- Verify a sending domain in the dashboard and add the SPF and DKIM DNS records your DNS provider requires.
- Generate an API key from the dashboard and store it as an environment variable in your application.
- Send your first message with the SDK for your language, or call the API endpoint directly with a HTTP request.
- Track delivery, opens, and bounces from the dashboard, or subscribe to webhooks for real-time events.
Product Information
A quick look at Resend's pricing, supported platforms, and performance.
Best for
The users, tasks, and scenarios where this tool fits best.
Users
- Backend developers
- Startup teams shipping fast
- Product managers who own onboarding flows
Tasks
- Password resets and login codes
- Order confirmations and receipts
- Newsletter broadcasts
Scenarios
- Wiring email into a new SaaS product before launch
- Migrating off a legacy SMTP relay
- Building with AI agents
Key features
Clean HTTP API and Official SDKs
Resend's main draw is that sending mail takes one call. You authenticate with a Bearer API key against the API endpoint, pass a from address, a recipient, a subject, and a body, and the message goes out. Official SDKs wrap that call in idiomatic code for six languages. Batch sending pushes up to 100 messages in a single request. For teams used to fighting SMTP, the difference is noticeable.
React Email Templates
React Email is an open source component library built by the same team. You write templates as React components, and the library handles the awkward HTML that email clients demand. That means reusable buttons, layouts, and sections instead of copy-pasted table markup. Big win. The components render consistently across Gmail, Outlook, and Apple Mail, which saves hours of testing on its own.
Deliverability and Domain Verification
Resend pushes hard on email deliverability, and most of that work happens in setup. You verify a domain by adding SPF and DKIM records, and you can configure DMARC to control how receivers treat unauthenticated mail. Once a domain is verified, Resend sends from it and watches how mailbox providers respond. The dashboard shows bounce and complaint data, so you catch reputation problems early instead of reading angry support tickets.
Webhooks and Event Tracking
Every message generates events: sent, delivered, opened, clicked, bounced, complained. You can subscribe to them through webhooks and route them into your own system. That matters when a bounced verification email should trigger a retry or a support ticket. The dashboard also keeps a live log of recent messages.
Inbound Email Processing
You can point MX records at Resend and receive mail too, not just send it. Inbound messages arrive through webhooks, which opens the door to reply handling, support inboxes, and agent-driven workflows. That's a less common feature among email APIs at this price point.
Marketing Tools and Automations
Beyond transactional mail, Resend handles contacts, segments, and broadcasts for marketing. Email automation lets you build recurring flows, and paid plans include a monthly pool of automation runs. Broadcasts only reach existing contacts, so you still need a way to collect opt-ins. Plan for that step early.
Command Line and MCP Access
There's a CLI for sending and testing from the terminal, and a remote MCP server that plugs Resend into Cursor, Claude, and other MCP clients. Building agent workflows? This lets the agent send, receive, and manage email through your connected account without custom glue code.
Pros and cons
Pros
- - The API is genuinely simple. SDKs cover six languages, and batch sending handles up to 100 messages per call.
- React Email makes reusable, client-safe templates far easier than hand-written HTML.
- The free tier is usable in production, capped at 3,000 emails per month and 100 per day.
- Webhooks expose the full event stream, so bounce and complaint handling fits into your own systems.
- Inbound email and a remote MCP server go beyond what most sending-only APIs offer.
Cons
- The free tier's 100 emails per day limit is easy to hit once real traffic starts, so most products move to a paid plan quickly.
- It's a sending platform, not a mailbox; your team still can't read and reply to mail the way you would in Gmail.
- Contacts, segments, and broadcasts are newer territory here, so teams doing heavy marketing may find dedicated tools more polished.
Frequently asked questions
Resend sends and receives application email programmatically. Typical uses are welcome messages, password resets, receipts, notifications, and newsletters. It's built for developers who want to call an API instead of running a mail server.
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