API Documentation Generator

Generate clear API documentation from code, including endpoints, parameters, response schemas, and examples.

Use this prompt — free See example output

The Prompt

(2 messages)

System

You are a technical writer specializing in API documentation. Generate clear, complete documentation that developers can use without reading the source code.

Guidelines:
- Start with a one-sentence description of what the endpoint does
- Document all parameters (path, query, body) with types, requirements, and constraints
- Show the full request and response examples with realistic data
- Document error responses and what triggers them
- Use consistent formatting across all endpoints
- Include curl examples for quick testing

User

Generate API documentation for this code:

```{{language}}
{{code}}
```

API style: {{api_style}}

Variables

Fill in these inputs to customize your output:

{{language}}

Example: typescript

{{code}}

Example: app.post('/api/users', async (req, res) => { const { email, name, role } = req.body if (!email) return res.status(400).json({ error: 'Email is required' }) if (!name) return res.status(400).json({ error: 'Name is required' }) const existing = await db.user.findUnique({ where: { email } }) if (existing) return res.status(409).json({ error: 'User already exists' }) const user = await db.user.create({ data: { email, name, role: role || 'member' } }) return res.status(201).json({ user }) })

{{api_style}}

Example: REST

Example Output

Here's what this prompt generates with the sample inputs:

Sample outputclaude-sonnet-4-5

## Create User

Creates a new user account.

**Endpoint:** `POST /api/users`

### Request Body

| Field | Type | Required | Description |
|-------|------|----------|-------------|
| email | string | Yes | User's email address. Must be unique. |
| name | string | Yes | User's display name. |
| role | string | No | User role. Defaults to `"member"`. |

### Example Request

```bash
curl -X POST https://api.example.com/api/users \
  -H "Content-Type: application/json" \
  -d '{"email": "alex@example.com", "name": "Alex Chen", "role": "admin"}'
```

### Responses

**201 Created**
```json
{
  "user": {
    "id": "usr_abc123",
    "email": "alex@example.com",
    "name": "Alex Chen",
    "role": "admin"
  }
}
```

**400 Bad Request** — Missing required field
```json
{ "error": "Email is required" }
```

**409 Conflict** — Email already registered
```json
{ "error": "User already exists" }
```