CotEditor

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

Source Code

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.

Development Environment

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

Contribution

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

How to Build

Build for ad‑hoc usage

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.

Build for distribution

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

License

© 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.