Paint.NET (sometimes stylized as paint.net) is a freeware general-purpose raster graphics editor program for Microsoft Windows, developed with the .NET platform.

Paint.NET originated as a computer science senior design project during spring 2004 at Washington State University.

[6] Initially, Paint.NET was released under a modified version of the MIT License, with the exclusion of the installer, text, and graphics.

[7] However, citing issues with the open source code being plagiarized by others that had rebranded the software as their own and bundled user content without their permission, the availability of the source code was restricted, in December 2007 Brewster announced his intent to restrict access to components of the program (including its installer, resources, and user interface).

In May 2007, Miguel de Icaza officially started a porting project called paint-mono.

[15] This project had partially ported Paint.NET 3.0 to Mono, an open-source implementation of the Common Language Infrastructure on which the .NET Framework is based.

[16] In 2010, developer Jonathan Pobst started a project called Pinta, describing it as a clone of Paint.NET for Mono and Gtk#.