# Contracts

- [Contracts Overview](/contracts/index.md)
- [Common](/contracts/common.md): PHP Common Contracts
- [Cookie](/contracts/cookie.md)
- [CQRS](/contracts/cqrs.md)
- [Filesystem](/contracts/filesystem.md)
- [Mailer](/contracts/mailer.md)
- [Pager](/contracts/pager.md)
- [Registry](/contracts/registry.md)
- [State Machine](/contracts/state-machine.md)