The easiest to use drawing library.
Grab the pencilJS.js file(or pencilJS.min.js for a compressed version), slap it to any HTML page and you’re good to go.
Check the quick start guide or the documentations for more informations.
You can also take a look at the examples’ folder.
For now, pencilJS can break other library or script you use. But, it’s planned to address that issue in the near future.
Any help is greatly welcomed, feel free to open a pull-request or fill an issue.