API Versioning Best Practices
💡 Concept Name
API Versioning – A strategy for managing breaking changes in APIs while preserving backward compatibility for existing consumers.
📘 Quick Intro
As APIs evolve, changes like renamed fields or updated logic may break client applications. API versioning allows you to maintain older versions while introducing improvements or breaking changes safely.
🧠 Analogy / Short Story
Imagine a software company releasing yearly editions: v1 is the original release, v2 adds new features, and v3 changes old behavior. Customers can stick with their preferred version without disruption. APIs work the same way.
🔧 Technical Explanation
- 📌 URI Versioning:
/api/v1/products - 📦 Header Versioning:
Accept: application/vnd.myapp.v2+json - 🎯 Query String Versioning:
?version=1(least preferred) - 📄 Media Type Versioning: Embedded in the MIME type
- 🔐 Best Practice: Prefer URI versioning for clarity; use header versioning in enterprise APIs for cleaner URLs.
🎯 Purpose & Use Case
- ✅ Allow multiple clients to use different versions without breaking functionality.
- ✅ Deploy new features and fixes without forcing every client to update immediately.
- ✅ Ensure backward compatibility for older apps still using deprecated formats.
💻 Real Code Example
// ASP.NET Core API versioning using URI
[ApiVersion("1.0")]
[Route("api/v{version:apiVersion}/products")]
public class ProductsV1Controller : ControllerBase
{
[HttpGet]
public IActionResult GetV1() => Ok("This is v1");
}
[ApiVersion("2.0")]
[Route("api/v{version:apiVersion}/products")]
public class ProductsV2Controller : ControllerBase
{
[HttpGet]
public IActionResult GetV2() => Ok("This is v2 with more data");
}
❓ Interview Q&A
Q1: Why is API versioning important?
A: It prevents breaking changes from affecting existing clients.
Q2: What is the most common versioning strategy?
A: URI versioning, like /v1, is the most widely used.
Q3: Can APIs have multiple active versions?
A: Yes, to support clients on different versions simultaneously.
Q4: Is query string versioning recommended?
A: No, it’s less intuitive and not cache-friendly.
Q5: What does header versioning provide?
A: Cleaner URLs and support for version negotiation via HTTP headers.
📝 MCQs
Q1. Which is a common way to version an API?
- Port number
- URI versioning
- File extension
- Database name
Q2. Which versioning method uses Accept headers?
- Query string
- Header versioning
- URI
- Response body
Q3. What is the least recommended versioning strategy?
- Header
- URI
- Query string
- DNS
Q4. How do you represent version 2 in URI versioning?
- /ver2
- /version/2
- /v2
- /2
Q5. Which versioning method is cleaner for enterprise APIs?
- Query versioning
- URI versioning
- File extension
- Header versioning
Q6. Is backward compatibility important in APIs?
- No
- Sometimes
- Yes
- Only for public APIs
Q7. What does media type versioning rely on?
- Path params
- DNS records
- MIME type
- Status codes
Q8. What is a benefit of URI versioning?
- Saves bandwidth
- Hides metadata
- Easy to understand
- Encrypts payloads
Q9. Which versioning approach is cache-friendly?
- Header
- Query
- Media type
- URI versioning
Q10. Which HTTP header is used in header versioning?
- Content-Type
- Authorization
- Accept
- Host
💡 Bonus Insight
You can combine URI and header versioning for internal vs public clients. For example, internal apps might use headers for flexibility while public APIs expose stable URI versions.
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