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codemirror/codemirror5

★ 27,246JavaScriptAudience · developerComplexity · 2/5MaintainedLicenseSetup · easy

TLDR

A code editor that runs in web browsers, letting you embed syntax-highlighted editing into any website without users installing anything.

Mindmap

mindmap
  root((repo))
    What it does
      Syntax highlighting
      Code editing in browser
      100+ language support
    Features
      Customizable themes
      Add-on extensions
      Programming API
    Use cases
      Online playgrounds
      Web-based IDEs
      Config editors
    Tech stack
      JavaScript
      npm packages
      CSS themes
    Audience
      Web developers
      App builders

Things people build with this

USE CASE 1

Build an online code playground where users can write and run code in their browser.

USE CASE 2

Create a web-based IDE or configuration tool that lets users edit code without installing software.

USE CASE 3

Add a code editor widget to a documentation site or template editor.

USE CASE 4

Embed syntax-highlighted code input into a web application with custom styling.

Tech stack

JavaScriptnpmCSS

Getting it running

Difficulty · easy Time to first run · 5min
Use freely for any purpose including commercial, as long as you keep the copyright notice.

In plain English

CodeMirror 5 is a code editor that runs inside a web browser. Instead of building your own text input area, you can embed CodeMirror into any web application and give users a full-featured editing experience, complete with syntax highlighting (color-coded text that helps visually distinguish different parts of code), support for over 100 programming languages, and add-ons for more advanced editing features. The problem it solves: plain text boxes (like the default input fields you see in web forms) have no understanding of code. CodeMirror brings a proper code editor experience directly into the browser, so you can add coding tools to any website or web app without requiring the user to install anything. You would use it if you're building a web application that needs users to write or edit code, for example, an online code playground, a web-based IDE (integrated development environment, meaning a full editor in the browser), a configuration tool, or a template editor. It's customizable through a programming interface and supports CSS-based themes, meaning you can style it to match your app. Note: this is version 5, which the project describes as legacy. A newer version (CodeMirror 6) exists and is described as more mobile-friendly and more actively maintained. This repository is the source code for version 5, written in JavaScript, and can be installed via npm (a standard JavaScript package manager).

Copy-paste prompts

Prompt 1
How do I embed CodeMirror 5 into my React app and set it up with JavaScript syntax highlighting?
Prompt 2
Show me how to create a custom theme for CodeMirror 5 using CSS.
Prompt 3
What add-ons are available for CodeMirror 5 and how do I install them via npm?
Prompt 4
How do I get the code a user typed into CodeMirror 5 and send it to my server?
Prompt 5
Can I use CodeMirror 5 to build a simple online code editor that supports multiple programming languages?
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Generated 2026-05-18 · Model: sonnet-4-6 · Verify against the repo before relying on details.