Lockfix is a Git-based CLI tool designed to revert `sha1` integrity changes in npm lock files, addressing the issue of constantly changing `integrity` properties due to various factors like different operating systems or npm versions. It works with both `package-lock.json` and `npm-shrinkwrap.json`, offering features like reverting changes from `sha512` to `sha1` while keeping untouched changes from `sha1` to `sha512`, and the ability to revert any changes made by the tool. This tool is ideal for developers who want to maintain the integrity of their npm lock files and ensure consistent builds across different environments.