Developer API Keys

Generate API keys to access your transactional email templates programmatically.

Overview

Learn about API keys and how they enable you to access transactional email templates programmatically.

What are API Keys?

API keys are secure tokens that allow your applications to authenticate with Letter's API. They're required to access your transactional email templates and send personalized emails.

  • Secure authentication for API requests
  • Access to transactional templates
  • Personalized email generation

Transactional Templates

Convert any newsletter into a transactional template that can be accessed via API. These templates support dynamic variables and can be personalized for each recipient.

  • Export newsletters as API-accessible templates
  • Support for dynamic variables and personalization
  • Real-time template rendering via API

How to get started

, then mark any newsletter as "transactional" in the editor. You'll be able to access it via API with your key and template ID.