API Testing & Debugging

Retrieve data from your endpoints

Create new resources

{
  "name": "John Doe",
  "email": "john@example.com"
}

Update entire resources

{
  "name": "John Smith",
  "email": "john.smith@example.com"
}

Remove resources

// GET request
const response = await fetch('http://localhost:3000/api/users');
const users = await response.json();

// POST request
const response = await fetch('http://localhost:3000/api/users', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    name: 'John Doe',
    email: 'john@example.com'
  })
});

Problem: "Access to fetch blocked by CORS policy"

Solution: Mock API Builder automatically handles CORS. If testing from a different domain:

• • Ensure your dev server is running on localhost
• • Check if you're using the correct port (3000)
• • CORS headers are automatically set for all origins

Problem: Endpoint returns 404 error

Checklist:

• ✓ Verify the endpoint path matches exactly
• ✓ Check if the project slug is correct
• ✓ Ensure the endpoint was saved in project settings
• ✓ Confirm the HTTP method is enabled for this endpoint

Problem: Response is not valid JSON

Solution:

• • Check your schema definition for syntax errors
• • Ensure all mock data follows the schema
• • Look for missing commas or brackets
• • Use the JSON validator in the schema editor

Problem: API responses are taking too long

Solutions:

• • Reduce the number of mock records (try 100 instead of 10,000)
• • Simplify nested objects in your schema
• • Use pagination for large datasets
• • Check database connection in logs