Culls is a CLI tool that optimizes package.json files by removing unnecessary fields before publishing to NPM, creating the smallest possible package.json for distribution. It's designed for Node.js developers and package maintainers who want to reduce their published package size by automatically stripping out development-specific dependencies and configurations like devDependencies, testing frameworks, and linting configs while preserving essential publishing fields. The tool is particularly useful for automated publishing workflows and can be integrated with GitHub Actions to streamline the package release process.