Resend Provider

Workers Auth integrates with Resend for sending magic link emails. Resend offers a generous free tier and a clean API, making it the recommended email provider.

Setup

1. Create a Resend account

Sign up at resend.com and verify your sending domain.

2. Create an API key

In the Resend dashboard, go to API Keys and create a new key.

3. Set the secret

wrangler secret put RESEND_API_KEY

4. Configure the provider

import { ResendProvider } from 'workers-auth/providers/resend';

ResendProvider({
  apiKey: process.env.RESEND_API_KEY!,
  from: 'auth@yourdomain.com',
});

Configuration

Option	Type	Description
apiKey	string	Your Resend API key
from	string	Sender email address (must be from a verified domain)

Use with MagicLinkStrategy

import { MagicLinkStrategy } from 'workers-auth/authn/magic-link';
import { ResendProvider } from 'workers-auth/providers/resend';
import { defaultTemplate } from 'workers-auth/templates/default';

MagicLinkStrategy({
  provider: ResendProvider({
    apiKey: process.env.RESEND_API_KEY!,
    from: 'auth@yourdomain.com',
  }),
  template: defaultTemplate,
});

EmailProvider interface

The Resend provider implements the EmailProvider interface:

interface EmailProvider {
  send(options: {
    to: string;
    subject: string;
    html: string;
  }): Promise<void>;
}

Writing a custom provider

To use a different email service (SendGrid, Mailgun, AWS SES, etc.), implement EmailProvider:

import type { EmailProvider } from 'workers-auth';

const sendgridProvider: EmailProvider = {
  async send({ to, subject, html }) {
    await fetch('https://api.sendgrid.com/v3/mail/send', {
      method: 'POST',
      headers: {
        Authorization: `Bearer ${SENDGRID_API_KEY}`,
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        personalizations: [{ to: [{ email: to }] }],
        from: { email: 'auth@yourdomain.com' },
        subject,
        content: [{ type: 'text/html', value: html }],
      }),
    });
  },
};

Pass your custom provider to MagicLinkStrategy:

MagicLinkStrategy({
  provider: sendgridProvider,
  template: defaultTemplate,
});