CodeMirror
CodeMirror is a versatile, embeddable code editor component for web applications, implemented in JavaScript. It provides syntax highlighting, code folding, autocompletion, and other advanced editing features for over 100 programming languages and markup formats. It is widely used to create in-browser code editors in documentation sites, online IDEs, and educational platforms.
Developers should use CodeMirror when they need to integrate a feature-rich, customizable code editor into a web application without building one from scratch. It is ideal for use cases like online code playgrounds (e.g., JSFiddle), documentation with live examples, or educational tools where users can edit and run code directly in the browser. Its extensive plugin ecosystem and theming support make it adaptable to various project requirements.