What is api-versioning-strategy?

A guide to managing multiple versions of an API, the interface that software uses to communicate with other software. It covers URL or header versioning, compatibility, deprecation, and migration plans.

Use it when designing a new API, adding incompatible changes, supporting several versions, routing versioned requests, or preparing migration documentation.

It helps you introduce breaking changes without unexpectedly disrupting existing clients. It also provides a way to retire old endpoints in an organized manner.

api-versioning-strategy — Skill for Claude Code and Codex by aj-geddes

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add aj-geddes/useful-ai-prompts --skill api-versioning-strategy

Clone the repo

git clone --depth 1 https://github.com/aj-geddes/useful-ai-prompts

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/api-versioning-strategy/github.svg)](https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/api-versioning-strategy)

Your own site

<a href="https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/api-versioning-strategy"><img src="https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/api-versioning-strategy/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/api-versioning-strategy"><img src="https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/api-versioning-strategy.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 918 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

Socket pass 16 Sept 2026
Snyk pass 16 Sept 2026

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00048	$0.00918
Opus 5.5	$0.00019	$0.00367
Sonnet 5.5	$0.00010	$0.00184
Haiku 4.5	$0.00005	$0.00092

Measured 2mo ago against content hash 248c92d1d3c6, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

api-versioning-strategy scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate-api.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/api-versioning-strategy/SKILL.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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: "[email protected]" }],
  });
});

// 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

Read the full file on GitHub · 117 lines

Files

What ships with it

14 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 117 lines · 48 tokens per session scan A 248c92d1d3c6

Subscribe to this mod's changes

api-versioning-strategy is a skill published in the GitHub repository aj-geddes/useful-ai-prompts (376 stars, last pushed 8mo ago), licensed MIT. It adds 48 tokens to every session and 918 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Backend and APIs

api-versioning-strategy next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
api-versioning-strategyaj-geddes/useful-ai-prompts	Skill	376	8mo ago	MIT	A	48	Claude Code, Codex
mem0-oss-to-platformmem0ai/mem0	Skill	68k	2d ago	Apache-2.0	A	217	Claude Code, Codex
azure-mgmt-botservice-dotnetmicrosoft/skills	Skill	3.2k	yesterday	MIT	A	78	Claude Code
fastapi-router-pymicrosoft/skills	Skill	3.2k	yesterday	MIT	A	46	Claude Code
dev-runtimelangwatch/langwatch	Skill	5.0k	yesterday	Apache-2.0	A	172	Claude Code
api-designericrisco/rsc-harness	Skill	503	2d ago	MIT	A	105	Claude Code, Codex
migrate-segw-to-raparc-mcp/arc-1	Skill	252	yesterday	MIT	A	106	Claude Code

api-versioning-strategy