API Versioning Strategy

Table of Contents

• Overview
• When to Use
• Quick Start
• Reference Guides
• 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:

Guide	Contents
Versioning Approaches	Versioning Approaches
Backward Compatibility Patterns	Backward Compatibility Patterns
Deprecation Strategy	Deprecation Strategy
Migration Guide Example	Migration Guide Example
Response Structure	Response Structure
Date Format	Date Format, Error Format
JavaScript/TypeScript	JavaScript/TypeScript, Python
GraphQL Versioning	GraphQL Versioning
gRPC Versioning	gRPC Versioning
Version Detection & Routing	Version Detection & Routing
Testing Multiple Versions	Testing Multiple Versions
Pattern 1: Version-Agnostic Core	Pattern 1: Version-Agnostic Core, Pattern 2: Feature Flags for Gradual Rollout, Pattern 3: API Version Metrics

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