API Versioning Approaches

Why Version APIs?

APIs evolve. New features are added, endpoints change, and data structures are enhanced. Versioning allows you to iterate while maintaining backward compatibility.

Versioning Strategies

URL Path Versioning

Version is part of the URL path.

/api/v1/users
/api/v2/users

Pros: Clear and obvious Cons: Creates duplicate code, verbose URLs

Query Parameter Versioning

Version specified as a query parameter.

/api/users?version=1
/api/users?version=2

Pros: Same base URL, cleaner URLs Cons: Less discoverable

Header Versioning

Version specified in HTTP headers.

Accept: application/vnd.company.v1+json
Accept: application/vnd.company.v2+json

Pros: Doesn't clutter URL space Cons: Not visible in browser, harder to test

Content Negotiation

Using Accept headers for different response formats.

Accept: application/json
Accept: application/xml

Best Practices

• Plan for evolution from the start
• Support multiple versions for a transition period
• Document version differences clearly
• Set deprecation timelines and communicate early
• Make breaking changes in major versions
• Use semantic versioning (v1.0.0)

Backward Compatibility Strategies

• Add new fields with default values
• Make new parameters optional
• Maintain old endpoints alongside new ones
• Use feature flags for gradual rollout
• Provide migration guides for clients

Deprecation Process

1. Announce the deprecation
2. Support old version for 6-12 months
3. Provide detailed migration documentation
4. Offer support during transition period
5. Finally, remove the old version