API Documentation Template

About This Template

Good API documentation is the single most important factor in developer adoption. This template provides a proven structure for creating clear, comprehensive, and maintainable API documentation. It is organized into sections that developers expect and can navigate quickly.

Template Structure

Section 1: Overview

Begin with a concise description of what your API does and who it is for.

Include the following:

• A one-paragraph summary of the API's purpose
• The base URL for all API requests (e.g., https://api.yourservice.com/v1)
• Supported response formats (typically JSON)
• A link to your changelog or release notes
• Contact information or a link to your support channels

Example:

The Acme API provides programmatic access to manage widgets, users, and billing. All requests are made to https://api.acme.com/v1 and return JSON responses. This documentation covers version 1 of the API.

Section 2: Authentication

Explain how developers authenticate their requests.

• Describe the authentication method (API key, OAuth2, JWT)
• Show exactly where credentials go (header, query parameter, body)
• Provide a complete request example with authentication included
• Link to your guide on obtaining credentials

Example:

Include your API key in the Authorization header of every request:

Authorization: Bearer YOUR_API_KEY

Section 3: Errors

Document your error response format and common error codes.

Standard error response format:

{
  "error": {
    "code": "invalid_request",
    "message": "The 'email' field is required.",
    "status": 400
  }
}

Common error codes to document:

Section 4: Rate Limiting

Explain your rate limiting policy.

• Requests per minute or second allowed per key
• Headers returned with rate limit information
• What happens when the limit is exceeded
• How to request a higher limit if needed

Section 5: Pagination

Describe how paginated responses work.

• The pagination strategy (cursor-based, offset-based)
• Query parameters for controlling pagination (limit, offset, or cursor)
• Response fields that indicate pagination state (next_cursor, has_more, total)
• A complete example of paginating through results

Section 6: Endpoint Reference

For each endpoint, provide the following:

Endpoint header:

POST /v1/widgets

Description: A brief explanation of what the endpoint does.

Request parameters:

Request example:

{
  "name": "Super Widget",
  "color": "red",
  "quantity": 5
}

Response example:

{
  "id": "wdg_abc123",
  "name": "Super Widget",
  "color": "red",
  "quantity": 5,
  "created_at": "2026-01-10T12:00:00Z"
}

Error responses: List endpoint-specific errors beyond the common ones.

Section 7: Webhooks

If your API supports webhooks, document them thoroughly.

• How to register a webhook URL
• Available event types and their payloads
• How to verify webhook signatures
• Retry policy for failed deliveries
• Example payload for each event type

Section 8: SDKs and Libraries

List official and community SDKs with installation instructions.

• Language-specific SDK names and package manager commands
• Links to SDK source code repositories
• Quick start examples for each supported language

Writing Tips

1. Lead with examples. Developers often scan for code samples first and read prose second.
2. Keep it current. Outdated documentation is worse than no documentation. Automate generation where possible.
3. Use consistent terminology. Define terms once and use them consistently throughout.
4. Provide a quickstart. Include a "make your first request in 5 minutes" guide at the top.
5. Test your examples. Every code sample should be a working, copy-pasteable example.

How to Use This Template

1. Download the Markdown template using the link above
2. Fill in each section with your API's specific details
3. Add endpoint documentation for every public endpoint
4. Have a developer unfamiliar with your API review the documentation for clarity
5. Publish using a documentation platform such as Mintlify, ReadMe, or a static site generator