CodeMirror is a code editor component for the web. It can be used in websites to implement a text input field with support for many editing features and has a rich programming interface to allow further extension.

Main features include:

• Works well with screen readers and keyboard-only users.
• Use the platform's native selection and editing features on phones.
• Support mixing of right-to-left and left-to-right text.
• Color code to reflect syntactic structure.
• Display gutters with line numbers or other information next to the code.
• Provide language-specific completion hints in the editor.
• Temporarily hide parts of the document.
• Editor-specific search, regexp search, and replace functionality.
• Detailed parse trees allow many types of language integration.
• Robustly implement demanding editor extensions.
• Most features are implemented on top of a generic public API.
• Remains responsive even on huge documents and long lines.
• Automatically insert matching brackets during typing.
• Show error and warning messages in the editor.
• Mix font styles and sizes, add widgets in the content.
• Import or create custom visual editor styles.
• Allow multiple users to edit the same document.
• Undo and redo functionality with collab editing support.
• Select and edit multiple ranges of the document at once.
• Provide custom text to display or announce to the user.
• Find a full description of the library's features in the docs.

CodeMirror is open source under a permissive license (MIT) and is being developed on GitHub. Contributions are welcome.