This repository is a curated collection of website-specific 'quirks' (hard-coded behaviors) for password managers, maintained by Apple. It contains structured JSON datasets including password rules (to generate compatible passwords), shared credential relationships (domains that share login backends), change-password URLs, 2FA appending sites, and web browser extension distribution information. The repo also includes reference implementations: a Password Rules language parser (JavaScript) and a regex-to-Password-Rules converter, along with validation and formatting scripts. While primarily a data curation project, the tools are reusable components for any password manager implementation. The data is validated against JSON schemas and linted in CI, ensuring high quality. The repository is actively maintained with frequent contributions from the community.