Free API Documentation Outline Generator
Generate professional API documentation instantly. Create developer-friendly docs with authentication guides, endpoint specs, code examples, and OpenAPI schemas. Perfect for REST, GraphQL, and Webhook APIs.
Documentation ready in minutes, not days
Code examples in multiple languages
Generates OpenAPI 3.0 spec outline
API Configuration
Format: GET /path Description
Generated Documentation
Fill in your API details and click "Generate API Documentation"
Why We Lost 47% of Developers (Bad API Docs)
March 2025. We launched our API. Got 10,000 developer signups in week one. By week four, only 5,300 were still active. We lost 47% of developers in 3 weeks.
The problem? Our API docs were terrible. No code examples. Confusing authentication. Unclear error messages. Developers tried our API, got frustrated, and left for competitors with better docs.
We rewrote our documentation using a structured approach. Developer retention jumped to 89%. Same API. Just better docs.
Good API Docs vs Bad API Docs:
"Send a POST request to /api/users with user data. Returns user object."
What's wrong: No example request/response. What user data? What format? What auth? Developers have to guess.
POST /api/users
Headers: Authorization: Bearer YOUR_TOKEN
Body: {'email':'user@ex.com','name':'John'}
Response 201: {'id':'123','email':'user@ex.com','name':'John'}
+ Code examples in JS, Python, cURL
Developer can copy-paste and test in 30 seconds. Success on first try.
The 8 Must-Have Sections in API Documentation:
1. Authentication Guide (MOST IMPORTANT)
Why it matters: 80% of developer friction happens here.
Must include: How to get API key/token, where to put it (header/query), full working example, what happens if auth fails
Bad: "Use API key for authentication"
Good: Step-by-step: 1) Get key from dashboard 2) Add to header: X-API-Key: your_key 3) Test with this curl command
2. Quick Start / Getting Started
Developers want to make their first successful API call in under 5 minutes. Provide a "Hello World" example that works immediately.
Include: Complete code snippet, expected response, link to full docs
3. Endpoint Reference (All Endpoints)
For EACH endpoint document:
• HTTP method and path (GET /users/:id)
• Description (what it does)
• Parameters (required vs optional, type, validation)
• Request body (if applicable)
• Response format (success + all error cases)
• Example request/response
4. Code Examples (Multiple Languages)
Include copy-paste ready examples in:
• JavaScript (fetch/axios) - most common
• Python (requests library)
• cURL (universal, works everywhere)
• Your users' primary language (Ruby, PHP, Go, etc.)
Why: Developers learn by example. Code examples = faster adoption.
Essential Documentation Elements
5. Error Codes & Troubleshooting
Every possible error with:
• HTTP status code (400, 401, 404, 500, etc.)
• Error message developers will see
• What caused it
• How to fix it
Example: 401 Unauthorized → "Invalid API key" → Check your key is correct and active
6. Rate Limiting & Quotas
Be transparent about limits:
• How many requests/minute or hour
• What happens when exceeded (429 error)
• How to check remaining quota (response headers)
• How to upgrade limits
Why: Prevents developers from hitting walls unexpectedly
7. Webhooks (if applicable)
If your API sends webhooks:
• Webhook event types
• Payload format
• How to verify signatures (security)
• Retry logic (what if webhook fails)
• Test webhook endpoints
8. Changelog & Versioning
Document all changes:
• New endpoints added
• Breaking changes (and migration guide)
• Deprecated features (with sunset date)
• Bug fixes
Why: Developers need to know when to update their code
API Documentation Tools:
- Swagger UI / Redoc: Interactive API docs from OpenAPI spec (auto-generated, always in sync)
- Postman Collections: Share collection of pre-configured requests developers can import
- ReadMe.com / GitBook: Hosted documentation platforms with search and versioning
- Stoplight / Apimatic: Full API design and documentation platforms
Testing Your API Docs:
Before publishing, ask someone unfamiliar with your API to:
- Make their first authenticated API call using only your docs
- Create a resource (POST request)
- Handle an error scenario
- Time them. If it takes more than 10 minutes, your docs need work.
Use this generator to create comprehensive API documentation. Good docs = more developers successfully integrating your API = faster growth.
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