Text Template Transformation Toolkit (T4)
Original author(s)Novell, Xamarin, Microsoft
Initial release2005; 19 years ago (2005)
Stable release
v2.0.5 / June 13, 2019; 5 years ago (2019-06-13)[1]
Written inC#
Operating systemLinux, Windows
Platform.NET Framework,
.NET Core,
TypeSoftware framework
LicenseMIT License
WebsiteCode Generation and T4 Text Templates

Text Template Transformation Toolkit (usually referred to as "T4") is a free and open-source template-based text generation framework. T4 source files are usually denoted by the file extension ".tt".


T4 is used by developers as part of an application or tool framework to automate the creation of text files with a variety of parameters. These text files can ultimately be any text format, such as code (for example C#), XML, HTML or XAML.

T4 uses a custom template format which can contain .NET code and string literals in it, this is parsed by the T4 command line tool into .NET code, compiled and executed. The output of the executed code is the text file generated by the template.[2] By using the Text Transformation class, T4 can also be run entirely from within a .NET application, eliminating the need for the end user to have Visual Studio installed.

T4 is used within Microsoft in ASP.NET MVC for the creation of the views and controllers, ADO.NET Entity Framework for entity generation, and ASP.NET Dynamic Data.[3] It is also used outside of Microsoft in projects such as SubSonic.[4]

T4 templating is supported in Visual Studio, MonoDevelop and JetBrains Rider.[5]


There are four types of controls handled by the T4 template transformation engine.

Name Syntax Description
Directives <#@ ... #> Instructions for the transformation engine
Standard control blocks <# ... #> Code to be executed (e.g. loops)
Expression control blocks <#= ... #> Expressions evaluated and converted to a string
Class feature control blocks <#+ ... #> Class and function definitions


See also


  1. ^ "Tags · mono/t4 · GitHub". GitHub T4 repository. Retrieved 2020-01-06.
  2. ^ Web Templates (2013), Website templates, Website Templates South Africa, ISBN 978-1-4251-3374-0, retrieved 19 November 2013
  3. ^ "Fun with T4 templates and Dynamic Data - Angle Bracket Percent - Site Home - MSDN Blogs". Blogs.msdn.com. 2008-11-26. Retrieved 2012-05-17.
  4. ^ "SubSonic v3's T4 Templates « Daily Cycle". Gcapnias.wordpress.com. 2009-01-12. Retrieved 2012-05-17.
  5. ^ "Rider: The Cross-Platform .NET IDE from JetBrains".
  6. ^ "What's new in T4 in Visual Studio 2010 - [Profoundly Esoteric Image] - Site Home - MSDN Blogs". Blogs.msdn.com. 2010-04-15. Retrieved 2012-05-17.
  7. ^ "Code Generation and T4 Text Templates - Visual Studio (Windows)".
  8. ^ "Mono.TextTemplating". GitHub. 22 October 2021.
  9. ^ "ForTea". GitHub. 20 October 2021.