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Overview

The Flywheel Transactional Email API allows you to send emails programmatically to your users. There are two main ways to send transactional emails:
  1. Custom emails - Send emails with custom HTML content, text, and full control over email properties
  2. Template emails - Send emails using pre-built templates with dynamic variables

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Authentication

All transactional email endpoints require authentication using an API key and authentication type header. Include both headers in your requests: 
Authorization: YOUR_API_KEY
Auth-Type: api
Both headers are required for all API requests.

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Endpoints

The following endpoints are available with interactive API playground for testing:

Send Custom Email

Send emails with custom HTML content and full control over email properties

Send Template Email

Send emails using pre-built templates with dynamic variables

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Interactive API Playground

All endpoints include an interactive playground where you can test API calls directly from the documentation. The playground includes:
  • Live testing: Send real API requests with your authentication token
  • Code examples: Auto-generated code snippets in multiple languages (cURL, JavaScript, Python, PHP)
  • Request/Response validation: Real-time validation of request parameters and response formats
  • Authentication testing: Test with your actual API credentials in a secure environment

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Email Delivery

All emails are sent through our reliable email infrastructure powered by Resend. You’ll receive an email ID in the response that you can use to track delivery status.

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Rate Limits

Transactional email endpoints are subject to rate limiting to ensure fair usage and service reliability. Contact support if you need higher limits for your use case.

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Support

For questions about the Transactional Email API, contact our support team at support@flywheel.cx.