Every codebase carries migrations nobody wants to do by hand. A framework ships a new major version. GitHub deprecates an Actions syntax. A config format changes. An internal API gets renamed across four hundred files. Teams either grind through it manually or write one-off scripts they throw away afterwards.
Rewriter.org is the name for the tool that makes those migrations routine.
Declarative Code Transformation
A source-to-source rewriting framework parses code and configuration, applies declarative transformation rules, and writes out the changed files. Rules are packaged independently, so a migration written once can be shared and reused by everyone facing the same upgrade.
The command line explains itself. rewriter apply react-19 ./src upgrades a React project. Another rule set rewrites deprecated workflow steps; another converts a config format; another updates calls to a renamed SDK. Over time the rule library becomes the asset, a public catalog of known-good migrations maintained by the people who wrote the frameworks or the people who suffered through upgrading them.
AI coding assistants make this more valuable. They can draft transformation rules fast, but teams want the change itself applied by a deterministic engine they can review.
An Open-Source Name
Rewriter is one common English word with a precise meaning in compilers and tooling. The .org signals an open-source project and a community-run rule registry, which is how developer tools in this space earn trust. Short, memorable, and ready to become the default way codebases move between versions.