We're engineers, and Retool is built for engineers. So it's pretty flexible: the internals are all available for you to see and modify (every Retool app is serialized to a YAML blob, and can be synced bi-directionally to Git), you can write JS in most places, as well as import npm packages (everything inside {{ }} is sandboxed JS), the front-end components are extensible (you can import your own React, Vue, etc. components), and the back-end we're completely agnostic towards (we connect to any REST / GraphQL API, as well as most databases).