API Versioning Strategy

Table of Contents

• [Overview](#overview)

• [When to Use](#when-to-use)

• [Quick Start](#quick-start)

• [Reference Guides](#reference-guides)

• [Best Practices](#best-practices)

Overview

Comprehensive guide to API versioning approaches, deprecation strategies, backward compatibility techniques, and migration planning for REST APIs, GraphQL, and gRPC services.

When to Use

• Designing new APIs with versioning from the start

• Adding breaking changes to existing APIs

• Deprecating old API versions

• Planning API migrations

• Ensuring backward compatibility

• Managing multiple API versions simultaneously

• Creating API documentation for different versions

• Implementing API version routing

Quick Start

Minimal working example:

// express-router.ts

import express from "express";

const app = express();

// Version 1

app.get("/api/v1/users", (req, res) => {

  res.json({

    users: [{ id: 1, name: "John Doe" }],

  });

});

// Version 2 - Added email field

app.get("/api/v2/users", (req, res) => {

  res.json({

    users: [{ id: 1, name: "John Doe", email: "john@example.com" }],

  });

});

// Shared logic with version-specific transformations

app.get("/api/:version/users/:id", async (req, res) => {

  const user = await userService.findById(req.params.id);

  if (req.params.version === "v1") {

    res.json({ id: user.id, name: user.name });

// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Best Practices

✅ DO

• Version from day one (even if v1)

• Document breaking vs non-breaking changes

• Provide clear migration guides with code examples

• Use semantic versioning principles

• Give 6-12 months deprecation notice

• Monitor usage of deprecated APIs

• Send deprecation warnings to API consumers

• Support at least 2 versions simultaneously

• Use adapters/transformers for version logic

• Test all supported versions

• Log which API version is being used

• Provide migration tooling when possible

• Be consistent with versioning approach

❌ DON'T

• Change API behavior without versioning

• Remove versions without notice

• Support too many versions (>3)

• Use different versioning strategies in same API

• Break APIs without incrementing version

• Forget to update documentation

• Deprecate too quickly (<6 months)

• Ignore feedback from API consumers

• Make every change a new version

• Use version numbers inconsistently