CodeMirror

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What CodeMirror is

CodeMirror is a code editor component that developers can add to websites and extend through its API. Its editing tools include syntax highlighting, line numbers, autocompletion, code folding, search and replace, linting, and multiple selections. The project is organized as npm packages under the @codemirror scope, with extensions adding capabilities such as highlighting and undo history. Parser packages are listed for JavaScript, Python, Rust, SQL, HTML, CSS, and JSON. The site says the editor works with screen readers and keyboard-only users, and uses phones’ native selection and editing features. It also supports language servers and documents an option to set a Content Security Policy nonce for editor style sheets. CodeMirror is MIT-licensed, and commercial use is permitted; commercial users are socially, but not legally, expected to help fund maintenance. The free plan is listed as free. Questions go to the project forum, and bug reports to its issue tracker.

Who it suits

CodeMirror suits developers adding an extensible code editor to a website, especially those who need its listed editing tools or language parsers. Its accessibility features may also suit projects serving screen-reader and keyboard-only users.

What it does well

Free, MIT-licensed, and permits commercial use
Includes syntax highlighting, folding, and autocompletion
Parser packages cover several programming and markup languages
Supports screen readers and keyboard-only users
Offers extension and language server support

What to know first

The listed platforms are web and API

Plans

Plan	Billed and limits	Price
CodeMirror (MIT open-source library)	Web code editor component · MIT license · commercial use is permitted	Free

As codemirror.net lists them, read 11 Oct 2026. The maker's own page has the final word.

Getting started

Visit https://codemirror.net/.
Use the web editor component through its API.
Add the npm packages and extensions needed for the editing features you want.

Verdict

CodeMirror provides a broad set of editing features in a web editor component, with extensions for adding capabilities. Its MIT license permits commercial use, though the project socially expects commercial users to help fund maintenance.

Questions

How much does CodeMirror cost?

The listed plan is CodeMirror (MIT open-source library) at no cost.

Is CodeMirror open source?

Yes. It is MIT-licensed, and commercial use is permitted.

What platforms does it support?

Its listed platforms are API and web, with web given as the supported platform.

Can it be extended?

Yes. It has an API, supports extensions and language servers, and its npm packages provide added capabilities.

Where can users get help?

Questions go to the forum and bug reports to the issue tracker.

Facts from CodeMirror's own pages

Accessibility and mobile: The site says CodeMirror works with screen readers and keyboard-only users, and uses native selection and editing features on phones. · codemirror.net, 11 Oct 2026
Editing features: Features include syntax highlighting, line numbers, autocompletion, code folding, search and replace, linting, and multiple selections. · codemirror.net, 11 Oct 2026
Extensibility: The reference manual describes CodeMirror as a set of npm packages under the @codemirror scope, with features such as highlighting and undo history added through extensions. · codemirror.net, 11 Oct 2026
Extension support: Yes · github.com, 20 Sept 2026
Language server support: Yes · github.com, 20 Sept 2026
Language support: The site lists parser packages for languages including JavaScript, Python, Rust, SQL, HTML, CSS, and JSON. · codemirror.net, 11 Oct 2026
License and commercial use: The site describes CodeMirror as MIT-licensed and says commercial users are socially, but not legally, expected to help fund maintenance. · codemirror.net, 11 Oct 2026
Maker: The site says CodeMirror is developed on code.haverbeke.berlin and identifies Marijn Haverbeke as its maintainer on an older project page. · codemirror.net, 11 Oct 2026
Supported platforms: web · github.com, 20 Sept 2026
Security-related capability: The reference manual documents an option to provide a Content Security Policy nonce for editor style sheets. · codemirror.net, 11 Oct 2026
Support: The site directs questions to its forum and bug reports to its issue tracker; it does not list support response times or a current support price. · codemirror.net, 11 Oct 2026
What it does: CodeMirror is a code editor component for websites, with an API for extending it. · codemirror.net, 11 Oct 2026

Where CodeMirror stands on Freedom251

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