Small site / online database
October CMS is perfect for this (disclaimer: I'm one of its maintainers). It has a robust roles / permissions system, is highly extendable, based on Laravel, and extremely easy to get started quickly with. Check out the builder plugin to kickstart your development process (it's a visual scaffolding tool to build your own plugins). It's also extremely easy to use October without the frontend "cms" module entirely and just use the backend functionality for custom Web applications. 

Feel free to join the discord to ask more specific questions: https://octobercms.com/support