Post your favorite Open Source Library

Question

using third-party libraries in your projects can save you a lot of time and also make the projects bugs-free ,a Great Source for those awesome libraries is github,where you can find , use and contribute.we all have our favorite Open Source Libraries,so let's share it.
my favorite android libraries list :
- Glide : image loading and caching library
- ChatMessageView: Chat UI library for Android
- Pugnotification : A powerful library for creating notifications in android platform.

Answer 1

wavesurfer.js is a cool interactive audio visualization tool that I've been studying ... check it out!

https://www.javascripting.com/view/wavesurfer-js

Answer 2

@JMcQ nice one