jscodeshift

jscodeshift is an open-source command-line toolkit for running codemods, scripted AST-based find-and-replace transforms, across many JavaScript or TypeScript files at once instead of editing each file by hand. Meta (then Facebook) published the first version to npm in March 2015 and continues to maintain it on GitHub under the facebook org; it is free to use and requires no license or account. It supplies the parser, AST query API, and test runner that most published React and Next.js upgrade codemods are themselves built on top of — it is a building block for writing transforms, not a ready-made migration for any specific framework.