API Design Fundamentals

Good API design reduces integration bugs and speeds up delivery.

Basic design rules

• Keep naming consistent and predictable.
• Model resources clearly.
• Return meaningful status codes and error messages.
• Version breaking changes.
• Validate inputs at the boundary.
• Document with OpenAPI/Swagger.

Common pitfalls

• Overloading one endpoint for unrelated operations
• Returning different shapes for similar resources
• Missing pagination and filtering strategy
• Silent failures without error contracts

Resources

• Microsoft REST API Guidelines
• Zalando RESTful API Guidelines
• OpenAPI Specification