SVGs are awesome! Thanks to math and geometry, SVG graphics give us a standardized way to create images and icons on the web to be displayed at any size without any loss in image quality. Here's an interactive reference to the most popular and/or interesting parts of the SVG spec.
Online Photo Editor
Photopea.com is a free online tool for editing raster and vector graphics with support for PSD, AI, and Sketch files.
Free Stock Photos, Vectors, Cliparts, PSD & Icons
an illustration library of people and objects
A free and open source tool for optimizing images and vector graphics.
Standing on the shoulders of Scriptographer and making use of HTML5 standards, Paper.js is a comprehensive open source vector graphics scripting framework.