Introduction: Why API versioning matters
APIs evolve. New requirements, optimizations, and features demand changes — but those changes can break clients if unmanaged. API versioning is your safety net: it lets you update without disrupting existing applications.
What breaks when APIs change
When an API changes contract — field names, response formats, required parameters — client applications that rely on the old behavior might break instantly. That means customer downtime, support tickets, and potential revenue loss. A disciplined versioning strategy limits these risks.
Core versioning strategies
URL path versioning
The most visible method: Example: GET https://hub.juheapi.com/exchangerate/v2/convert?apikey=YOUR_KEY&base=BTC&target=USD Here, v2 in the path explicitly tells consumers which version they are using.
Pros:
- Clear in documentation and logs
- Easy routing at API gateway
Cons:
- Requires URL updates in clients
Query parameter versioning
Example: GET https://api.example.com/exchangerate/convert?version=2&apikey=YOUR_KEY
Pros:
- Keeps base path stable
- Can be easier for quick testing
Cons:
- Less visible in routing
- Can be missed in caching layers
Header-based versioning
Include a custom header: API-Version: 2
Pros:
- Keeps URLs clean
- Enables content negotiation
Cons:
- Not immediately visible in browser requests
Pros and cons of each approach
Each method has trade-offs. URL path versioning is the most explicit, query parameters offer flexibility, and headers are clean but may be hidden from plain view.
Designing for backward compatibility
- Avoid breaking changes where possible
- Add new fields without removing old ones
- Use defaults for new parameters
Version deprecation strategies
- Announce early
- Provide clear timelines
- Maintain old versions temporarily
Best practices checklist
- Document all versions clearly
- Test old versions alongside new ones
- Use semantic versioning to signal change impact
Final thoughts and resources
API versioning is key to sustainable API evolution. Learn more from resources like the Microsoft REST API Guidelines and Google API Design Guide.