Codemod — AI-Powered Code Migration CLI

Codemod — AI-Powered Code Migration Platform

The Problem

Upgrading frameworks (Next.js 12→13, React class→hooks, Express→Fastify) across hundreds of files is tedious and error-prone. Manual find-and-replace misses edge cases. AI chat can't handle 500-file refactors consistently.

The Solution

Codemod provides deterministic AST-based transformations enhanced with AI. Define migration rules once, run them across your entire codebase with confidence.

Key Features

• Codemod CLI — execute migrations from terminal or CI
• YAML Workflows — coordinate multi-step migrations with matrix strategies and approval gates
• ast-grep support — powerful AST pattern matching for precise code transformations
• Community Registry — discover and share codemods for popular migrations
• MCP Integration — use codemods from AI coding assistants
• Validation — dry-run mode, diff preview, and rollback support

Quick Start

# Run a community codemod (e.g., Next.js App Router migration)
npx codemod @codemod/next/13/app-router

# Initialize a new custom codemod
npx codemod init my-codemod

# Define a multi-step workflow
npx codemod workflow run -w my-codemod/workflow.yaml

# Publish your codemod to the registry
npx codemod publish my-codemod

# Search the registry
npx codemod search "react hooks"

Example: YAML Workflow

name: upgrade-nextjs-13
steps:
  - name: app-router
    codemod: @codemod/next/13/app-router
  - name: metadata
    codemod: @codemod/next/13/metadata
  - name: image-component
    codemod: @codemod/next/13/next-image

Popular Community Codemods

• Next.js App Router migration
• React class components → hooks
• Security patch automations
• TypeScript strict mode upgrades

FAQ

Q: What is Codemod? A: Codemod is an open-source CLI and platform for running AI-powered code migrations at scale. It uses AST-based transformations to safely refactor large codebases.

Q: Is Codemod free? A: Yes, fully open-source under Apache-2.0. The CLI and community registry are free.

Q: What languages does Codemod support? A: Any language supported by ast-grep, including JavaScript, TypeScript, Python, Go, Rust, Java, C, and more.