C# Academy · Lesson

API Versioning Strategies

Version via URL, header, and query string.

API Versioning Strategies is a free C# Academy lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the C# Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Why Version an API?

Once clients depend on your API, you cannot break its contract. Versioning lets you ship breaking changes in a new version while old clients keep working against the old one.

// v1 returns { name }
// v2 returns { firstName, lastName }  (breaking)

URL Path Versioning

The most visible strategy puts the version in the path. It is unambiguous and easy to route, browse and cache.

GET /api/v1/products
GET /api/v2/products

Query String Versioning

The version travels as a query parameter. URLs stay stable and a missing parameter can default to the latest or a fixed version.

GET /api/products?api-version=1.0
GET /api/products?api-version=2.0

Header Versioning

A custom request header carries the version, keeping the URL clean. The downside: it is invisible in a browser address bar and harder to test by hand.

GET /api/products
X-Api-Version: 2.0

Media Type Versioning

Also called content negotiation. The version is embedded in the Accept header's media type. It is the most RESTful but least discoverable option.

GET /api/products
Accept: application/json;v=2.0

Comparing the Strategies

Each strategy trades discoverability against URL cleanliness:

URL path: most discoverable, clutters URLs.
Query string: stable URLs, easy defaults.
Header: clean URLs, hidden from browsers.
Media type: purest REST, hardest to use.

// Many teams pick URL path for public APIs

Semantic Versioning of APIs

API versions are usually major-only (v1, v2). Reserve minor versions for additive, non-breaking changes that old clients can ignore.

// v1.0 -> v1.1 : additive (safe)
// v1   -> v2   : breaking (new version)

Deprecation

Never remove an old version abruptly. Mark it deprecated, advertise a sunset date, and signal it to clients via headers.

// Response header on a deprecated version:
// Sunset: Wed, 31 Dec 2026 23:59:59 GMT
// Deprecation: true

Default Version

Decide what happens when a client sends no version. Common choices: assume the latest, assume v1, or reject the request. Being explicit avoids surprises.

// Strategy: unversioned request -> treat as v1.0

Versioning the Right Things

Version the contract (routes, request/response shapes), not internal implementation details. A v2 endpoint can share most business logic with v1.

// Same service, two thin controllers:
// ProductsV1Controller, ProductsV2Controller

Mixing Strategies

ASP.NET Core's versioning library can read the version from several sources at once, letting clients pick whichever is convenient. You will configure this next.

// Accept version from URL OR header OR query

Quick Check

Test your understanding of versioning strategies.

Recap

You surveyed API versioning strategies:

URL path, query string, header, and media type.
Each trades discoverability against URL cleanliness.
Version the contract, deprecate gracefully, and define a default.

Next: configuring Asp.Versioning in ASP.NET Core.

Frequently asked questions

Is the “API Versioning Strategies” lesson free?

Yes — the full text of “API Versioning Strategies” is free to read here on the web, and the C# Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the C# Academy course, upgrade to CoddyKit PRO.

What will I learn in “API Versioning Strategies”?

Version via URL, header, and query string. You practise C# Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start C# Academy?

No prior experience is required. C# Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “API Versioning Strategies” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this C# Academy lesson?

Yes. Every C# Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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