I build custom user interfaces daily that interact with APIs using AngularJS framework mixed with custom jQuery and Javascript, Stylus CSS pre-processing, HTML5, CSS3 and Bootstrap 3. I use bower and NPM for package / dependency management, GIT for version control and Gulp for building my projects. I also use Laravel / Lumen PHP frameworks to build custom APIs and leverage Vagrant with VirtualBox to create spec development environments, Composer for PHP dependency management and some version of relational database for the data layer (MySQL, SQLite, PostgreSQL). I also use the full MEAN (MongoDB, ExpressJS, AngularJS, NodeJS) stack to build custom applications.
Also writing a little Pyth...