Molecule is great for building micro services or regular web applications. It is designed around simplicity, testability and freedom of choice. Built entirely using TDD it provides super-easy ways to test your application and individual endpoints, both in and out of container. Molecule is small - it weights less than 150k - and will stay as lean as possible. It is pluggable through the concept of middlewares (a.k.a filters). It offers various abstractions for a number of functionalities (such as routing, templating, security, etc.). You're free to use the built-in options or provide your own implementations.