Images, Videos, And Vector Graphics
Undraw.io – Free Vector Images
Illustrations,co – SVG & PNGs
PixaBay.com – Free Illustrations, Images, Videos, Music, Sound Effects
Pexel.com – Free Images – Real Photos
UnSplash.com – Free Images – Real Photos
VectorStock – Some Free – You can buy credits and purchase SVGs for about $1.00
Material Icons – Free
https://gauger.io/fonticon/ – Favicon Generator
CodeCogs has an Equation Editor to generate SVGs.
LottieFiles.com – A large collection of really cool animations.
UI/UX Mockup Tools
Figma – Alternative to Adobe XD. Free for individual use. Requires login.
Framer – Interactive mockups. Free for individual use. Requires login and some knowledge of how to code.
Charts.js – Beautiful opensource chart library.
D3.js – Amazing library and resource. Steep learning curve but absolutely worth it.
GreenSocks – for web animations.
Framer Motion for React.
Three.js – Awesome 3D library. Very much worth the learning curve.
CSS & General Coding Examples
https://codepen.io/ – Code Pen – Tons of really nice CSS, JS, & general code examples
Material – If you want to use Material UI then this is a great resource for the design philosophies behind it. There are many examples of do’s and don’ts when if comes to general UI design. This is information compiled over many years from top Graphic Designers and Developers at Google. View this free resource at https://material.io/design/
UI Packages – Not Free
Kendo UI offers a lot of components and tools for ASP.NET, JQuery, React, Angular, Vue, and Blazor. Their documentation is exceptional. The cost is around $1000 to $2200 annually. Check here for pricing.
Creative Tim has free and paid templates for JQuery, React, Angular and Vue.
CodeCanyon has very affordable templates to help you get started.
WrapBootstrap another good resource that sells templates.