CloudinaryA great image server. Developers use it to serve images. It allows the image to be transformed before sending it to the client. This is especially important when serving responsive images.
CodepenOnline playground to create html CSS and JavaScript projects. Use it to quickly experiment or see how others go about addressing certain issues.
CodesandboxOnline playground to create html CSS and JavaScript projects. Use it to quickly experiment or see how others go about addressing certain issues.
GlitchOnline playground to create html CSS and JavaScript projects, but also NodeJS apps. Use it to quickly experiment. However it's also possible to host anything you create.
ReplitIn browser IDE that supports over 50 languages. Replit is especially special since most of the tools listed here don't support backend that much. However I have to admit that I don't use this much.
JSFiddleAn online IDE for HTML, CSS and JavaScript snippets known as fiddles. The interface splits into four panes which can can resized.
StackBlitzStackBlitz's WebContainers tech is a novel approach to the online development environment space. These only work on chromium based browsers at the moment but the technology is very exciting.
CSS ShadowsFind the perfect shadows for your CSS styles. Use the handles to easily visualise the depth and blur levels of the shadows.
Cubic bezier toolA well known tool to find just the right Cubic Bezier curve for a given CSS animation.