explaingit

ajaxorg/ace

📈 Trending★ 27,133JavaScriptAudience · developerComplexity · 2/5ActiveLicenseSetup · easy

TLDR

A JavaScript code editor that runs in the browser with syntax highlighting for 120+ languages, themes, and features like code folding and multiple cursors.

Mindmap

mindmap
  root((Ace Editor))
    What it does
      Syntax highlighting
      Code folding
      Multiple cursors
      Search and replace
    Features
      120+ languages
      20+ themes
      Vim/Emacs modes
      Large file support
    How to use
      Embed in webpage
      Configure language
      Set theme
      Customize keybindings
    Use cases
      Online IDEs
      Config editors
      Template builders
      Code playgrounds

Things people build with this

USE CASE 1

Build an online coding environment where users write and test code directly in the browser.

USE CASE 2

Create a configuration file editor that highlights syntax and helps users avoid mistakes.

USE CASE 3

Add a code snippet editor to a documentation or learning platform.

USE CASE 4

Build a template or script builder tool with real-time syntax validation.

Tech stack

JavaScriptnpm

Getting it running

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

In plain English

Ace is a standalone code editor that runs inside a web browser, written in JavaScript. You can embed it into any website or web app and give users a full code-editing experience without requiring any external software installation. The problem it solves: standard HTML text areas are basic input boxes with no code intelligence. Ace brings a proper editor into the browser, comparable to desktop text editors, with syntax highlighting (color-coding) for over 120 programming languages, more than 20 visual themes, automatic indentation, code folding (collapsing sections of code), support for multiple cursors, and search-and-replace using regular expressions. It can handle very large files (the README notes 4,000,000 lines as an upper limit). Embedding it in a web page is straightforward: you include the script file and call a single function pointing at a div element on your page, and that div becomes an interactive code editor. You can then switch the language mode (to activate the right syntax highlighting), set a theme, and configure key bindings including vim and Emacs modes. You'd use Ace when building any web application that needs users to write or edit code directly in the browser, an online coding environment, a configuration editor, a template builder, or similar tool. It's a JavaScript library with no runtime dependencies, distributed via npm (Node.js's package manager), and licensed under BSD.

Copy-paste prompts

Prompt 1
Show me how to embed Ace editor into a simple HTML page and set it to JavaScript mode with the Monokai theme.
Prompt 2
How do I configure Ace editor to support vim keybindings and enable code folding for Python files?
Prompt 3
I need to load a large code file (100k+ lines) into Ace editor and let users search and replace text. What's the best way to do this?
Prompt 4
How can I programmatically get the current code content from an Ace editor instance and send it to my server?
Prompt 5
What's the simplest way to add Ace editor to a React component and sync its content with component state?
Open on GitHub → Explain another repo

Generated 2026-05-18 · Model: sonnet-4-6 · Verify against the repo before relying on details.