Emacs can compare two files and highlight their differences (M-x ediff)

GNU Emacs is an extensible, customizable text editor—and more. At its core is an interpreter for Emacs Lisp, a dialect of the Lisp programming language with extensions to support text editing. The features of GNU Emacs include:

    * Content-sensitive editing modes, including syntax coloring, for a variety of file types including plain text, source code, and HTML.
    * Complete built-in documentation, including a tutorial for new users.
    * Full Unicode support for nearly all human languages and their scripts.
    * Highly customizable, using Emacs Lisp code or a graphical interface.
    * A large number of extensions that add other functionality, including a project planner, mail and news reader, debugger interface, calendar, and more. Many of these extensions are distributed with GNU Emacs; others are available separately.


GNU Emacs

Windows

Linux

<p>GNU Emacs is an extensible, customizable text editor—and more.</p>

desktop

mobile

tablet

browser

console

wearable

indie

custom

Online

Android

iPhone

iPad

Android Tablet

Self-Hosted

Software as a Service (SaaS)

Chrome OS

Windows Phone

Google Chrome

Firefox

Steam

Kindle Fire

Blackberry

Windows Mobile

Windows S

Wordpress

Apple Watch

PortableApps.com

Magento Community Edition

Apple TV

Opera

Xbox

Playstation

Android Wear

Safari

Java Mobile

Symbian S60

JavaScript

Wine

Blackberry 10

Xfce

Python

Node.JS

Facebook

Java

Haiku

HP webOS

Slack

.NET Framework

Raspberry Pi

Microsoft Office Outlook

Shopify

Internet Explorer

Apps with 'IDE All Languages' feature

GNU Emacs