These days, almost every developer is familiar with the benefits of open source and code authoring tools. Open source repositories such as GitHub and SourceForge provide valuable resources for those who seek help in building their own applications.
1. Atpad
designed for developers who prefer to use a text editor rather than a mature IDE, Atpad provides a tabbed environment, line numbering, bookmarks, code snippets System, unlimited undo/Redo, and more.
Supported operating systems: Windows
2. Codemirror
JavaScript-based codemirror can embed a text editor in a Web browser. It supports more than 90 languages, with AutoComplete, code folding, parentheses and tag matching, and more.
Supported operating systems: OS-Independent
3. Emacs
Since the 70 's, generations of developers have used Emacs to write code. It provides content-sensitive editing, syntax coloring, comprehensive Unicode support, custom features, and a huge library of plugins.
Supported operating systems: Windows, Linux, and OS X
4. JEdit
This Java-based text editor supports more than 200 programming languages. It includes a built-in macro language that provides hundreds of pre-written macro commands and plugins.
Supported operating systems: OS-Independent
5. notepad++
The Scintilla-based notepad++ was recently updated earlier this month, adding new Ghost input features. Other features include syntax highlighting and folding, customizable GUI, Document Map, AutoComplete, tabbed interface, WYSIWYG printing, bookmarks, macros, and more.
Supported operating systems: Windows
6. TEA
This fast cross-platform text editor claims to have hundreds of supported features. Although small, it contains spell checker, tabbed layouts, syntax highlighting in dozens of languages, support for code snippets and templates, bookmarks, calendars, and more.
Supported operating systems: Windows, Linux, and OS X
7. TextMate
This text editor is only for Mac, claiming to be bringing code and tags into the 21st century. Please note: This is an open source tool, but it may not be free;
Supported operating systems: OS X
8. Vim
Vim is a mature text editor with many hardcore fans and an old enemy of Emacs. It's easy to configure, sometimes called the programmer's editor, because it has many of the features of the standard IDE. It is a charitable software, so the people who use it are asked to donate money to an institution that helps poor children in Uganda.
Supported operating systems: Windows, Linux, and OS X
9. XML Copy Editor
this fast and lightweight editor is ideal for a task: writing valid XML code. Features include syntax highlighting, folding, tagging, spelling and styling checks, and importing and exporting from Microsoft Word.
Supported operating systems: Windows and Linux
Source: 51CTO
The programmer's Favorite 9 text editor
