When will you use this?

Use Web API when a website, mobile app, or React frontend needs JSON from your server.

• Mobile apps and React frontends call your ASP.NET Core API over HTTP with JSON.
• JWT tokens prove who the user is on every protected API request.

Real-world: HDFC-style net banking API

The Banking team building HDFC-style net banking API uses API Versioning to ship /api/v2/orders without breaking old mobile clients. account holders never see the C# code — they just get a fast, reliable transfer endpoints and account balance.

Production-style code

[ApiController]
[Route("api/[controller]")]
public class SampleController : ControllerBase
{
    [HttpGet]
    public IActionResult Get() => Ok(new { topic = "API Versioning" });
}

What happens in production: In HDFC-style net banking API, getting API Versioning right means account holders trust the transfer endpoints and account balance every day.

Lesson example (start here)

Copy this smaller example first. Once it works, compare it with the real-world code above.

[ApiController]
[Route("api/[controller]")]
public class SampleController : ControllerBase
{
    [HttpGet]
    public IActionResult Get() => Ok(new { topic = "API Versioning" });
}

Line-by-line walkthrough

How it works (big picture)

• Study the example line by line.
• Each part connects to API Versioning.
• Edit one line, save, run dotnet run, and see what changes.

Do this on your computer

1. Add or update an API controller action.
2. Test with Swagger or Postman.
3. Check status codes and JSON shape match the lesson.
4. Read the real-world section and name which part of the app uses this topic.
5. Run the example locally with dotnet run and confirm the same behavior.
6. Change one value in the example (route, text, or connection string) and predict what will happen before you save.

Experiments — try changing this

• Change a string or route in the example and save — watch the browser or Swagger response update.
• Break the code on purpose (remove a semicolon), read the error message, then fix it.
• Change the URL path and update the browser address to match.
• Use dotnet watch run while editing API Versioning — the app restarts on save.

Remember

You learned what API Versioning is and when to use it in ShopNest. Practice by changing the example yourself. Use the Next link when you can explain it in your own words.

Common questions