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📬

Resend

Messaging

Modern developer-first email API for transactional & marketing emails

Resend provides clean, reliable email sending infrastructure with modern React Email support, domain verification, and webhooks.

Details

Auth Type
API Key (Bearer token)
Rate Limit
10 emails/sec
Pricing
Free tier (3,000 emails/mo); paid from $20/mo
Full Docs
Step 1: Save your provider key

This is NOT your Callio key. Enter the API key from the provider's dashboard (e.g. OpenAI/SendGrid).

API Key (Bearer token)

1. Go to https://resend.com/api-keys 2. Create API Key with Sending access 3. Paste into Callio

Get API Credentials

Getting Started

1

Try It Instantly

Click "Try It" above to test the API in the playground

2

Add to Your Agent

Click "Add to Agent" to get your API key and integrate

Common Use Cases

Transactional emails
Password reset links
Agent notification alerts
Newsletter delivery

💻 Code Examples

Get started quickly with these code examples in your favorite language

curl -X GET \
  'https://www.callio.dev/api/proxy/resend/forward?target=https%3A%2F%2Fapi.resend.com%2Fendpoint' \
  -H 'Authorization: Bearer YOUR_CALLIO_KEY' \
  -H 'Content-Type: application/json'

💡 Tip: Replace YOUR_CALLIO_KEY with your actual Callio API key from the dashboard.

Ready to integrate Resend?

Test endpoints live or generate your API key and start building in minutes

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