CotEditor is a lightweight plain-text editor designed for macOS. The project aims to provide a general plain-text editor for everyone with an intuitive macOS-native user interface.

• Requirement: macOS Sequoia 15 or later
• Web Site: https://coteditor.com
• Mac App Store: https://apps.apple.com/app/coteditor/id1024640650
• Languages: English, Czech, Dutch, French, German, Italian, Japanese, Korean, Polish, Portuguese, Spanish, Simplified Chinese, Traditional Chinese, and Turkish

CotEditor is a purely macOS native application written in Swift. It adheres to Cocoa's document-based application architecture and respects the power of NSTextView and related text system APIs.

• macOS Tahoe 26
• Xcode 26.1
• Swift 6.2 (partly in Swift 5 mode)
• Sandbox and hardened runtime enabled

CotEditor has its own contributing guidelines. Read CONTRIBUTING.md through before you create an issue or make a pull request.

For those people who just want to build and play with CotEditor locally.

1. Open CotEditor.xcodeproj in Xcode.
2. Switch to ad-hoc build mode:
   1. Open Configurations/CodeSigning.xcconfig.
   2. Comment out #include "CodeSigning-Default.xcconfig".
   3. Uncomment #include "CodeSigning-AdHoc.xcconfig".
3. Build the “CotEditor” scheme.

1. Open CotEditor.xcodeproj in Xcode.
2. Build the “CotEditor” scheme.

© 2005-2009 nakamuxu, © 2011, 2014 usami-k, © 2013-2025 1024jp.

The source code is licensed under the terms of the Apache License, Version 2.0. Image resources are licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. See LICENSE for details.