The jsPlumb Toolkit is an advanced, standards-compliant and easy to use library for building Javascript connectivity based applications
1-5 developers $3500
Anime.js is a lightweight JavaScript animation library with a simple, yet powerful API. It works with CSS properties, SVG, DOM attributes and JavaScript Objects.
KUTE.js is a Javascript animation engine with top performance, memory efficient & modular code. It delivers a whole bunch of tools to help you create great custom animations.
A lightweight JavaScript library for creating particles.
Typed.js is a library that types. Enter in any string, and watch it type at the speed you've set, backspace what it's typed, and begin a new sentence for however many strings you've set.
More: https://cssauthor.com/javascript-animation-libraries/
Django REST framework is a powerful and flexible toolkit for building Web APIs.