CodeMirror

CodeMirror is a versatile, extensible code editor component for the web, maintained by Marijn Haverbeke and used by thousands of websites and applications to implement feature-rich text input fields with advanced editing capabilities. The current major version, CodeMirror 6, represents a complete rewrite from the ground up with a modular, functional architecture based on immutable document models and a transaction-based state management system, enabling efficient incremental rendering and collaborative editing support. CodeMirror 6 offers first-class accessibility support that works well with screen readers and keyboard-only users, full mobile device support that leverages the platform native selection and editing features on phones and tablets, bidirectional text support for mixing right-to-left and left-to-right text, syntax highlighting through the Lezer parser system that supports incremental parsing for large documents, line numbers and customizable gutters, autocompletion with language-specific completion hints, code folding, multiple selections and multi-cursor editing, search and replace, bracket and tag matching, drag-and-drop text editing, custom keybindings, and theming. The editor is split into small npm packages (@codemirror/state, @codemirror/view, @codemirror/commands, @codemirror/language, @codemirror/autocomplete, @codemirror/search, @codemirror/lint) allowing developers to bundle only the functionality they need, keeping bundle sizes minimal. Language packages are available for JavaScript, TypeScript, Python, HTML, CSS, JSON, Markdown, SQL, Java, C++, Rust, Go, PHP, and many more. CodeMirror 5, the previous version, remains maintained for backward compatibility. The project is open-source under the MIT License and has been adopted by major platforms including Chrome DevTools, Adobe Brackets, Light Table, CodePen, JSFiddle, Replit, GitLab, JupyterLab, and Obsidian.