API Design Principles

API Design Principles

Master REST and GraphQL API design principles to build intuitive, scalable, and maintainable APIs that delight developers and stand the test of time.

Use this skill when

• Designing new REST or GraphQL APIs
• Refactoring existing APIs for better usability
• Establishing API design standards for your team
• Reviewing API specifications before implementation
• Migrating between API paradigms (REST to GraphQL, etc.)
• Creating developer-friendly API documentation
• Optimizing APIs for specific use cases (mobile, third-party integrations)

Do not use this skill when

• You only need implementation guidance for a specific framework
• You are doing infrastructure-only work without API contracts
• You cannot change or version public interfaces

Instructions

1. Define consumers, use cases, and constraints.
2. Choose API style and model resources or types.
3. Specify errors, versioning, pagination, and auth strategy.
4. Validate with examples and review for consistency.

Refer to resources/implementation-playbook.md for detailed patterns, checklists, and templates.

Resources

• resources/implementation-playbook.md for detailed patterns, checklists, and templates.

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.