Licensing Options

PostSharp 1.0-1.5 is provided to you under a commercial/GPL-LGPL dual license. PostSharp redistributables (PostSharp.Public.dll and PostSharp.Aspects.dll) are licensed under LGPL. This is not a viral license, so it does not affect the licensing of your own code.

If you need to redistribute build-time components (PostSharp.Core.dll), and don't want to release your product under an open-source license, you have to acquire a redistribution license.

If you are brave, you can read the full open-source license agreement (PDF).

Licensing details of PostSharp 2.0 are not yet available and, therefore, PostSharp 2.0 licenses cannot be acquired yet. Please contact us by phone or mail if you want to discuss it.

Frequently Asked Questions


Can I use PostSharp for free to build commercial software?

Yes. You can use PostSharp for free to build commercial software as long as your software does not require the library PostSharp.Core.dll. Most of the time, your software is only linked to PostSharp.Public.dll and PostSharp.Laos.dll.

So when do I have to pay for PostSharp?

You have to pay for PostSharp when your software requires PostSharp.Core.dll. So if you distribute developer tools that uses PostSharp to perform analysis and transformation of assemblies of your customers (for instance an O-R framework or an application server), and do not release your product exclusively under an OSI-recognized license, you need to buy a commercial license.

My company has developed a plug-in referencing PostSharp.Core.dll. It is for internal use only. Do I need to acquire a commercial license?

No, since you don't distribute the plug-in outside your company.

I need to redistribute PostSharp.Core.dll to my customers. When do I need to acquire a commercial license?

As soon as you distribute your product outside your company (for any reason: testing, general distribution or whatever else). If your product remains inside your company, it is not 'contaminated' by GPL.

I made a plug-in for PostSharp and want to release it as open source. But I don't like GPL...

You can release your plug-in under any open-source license recognized by the Open-Source Institute. However, code linked to your plug-in will have to be released under OSS as well, because the PostSharp license is contagious even indirectly.

Policies of my company forbid the use of projects licensed under GPL or LGPL. Do you release PostSharp under a different license?

Yes. Please contact us and we will discuss it directly.


Do you provide commercial support?

Yes. We provide two levels of commercial technical support.

Does any other company provides commercial support?

Not that we know.


How old is the project?

The project started in September 2004 as a hobby project. It took 2 years to build PostSharp Core, 1 year to build PostSharp Laos and finalize the product, and 1 year to stabilize it and market it.

So the project is not exactly young, even if it has become popular quite recently.

How do you make money out of PostSharp?

Well, currently we don't make a lot. We sell some commercial licenses, but the project is still financed from consulting.

We are in the process of creating a company that will sell a commercial edition of the product, and make the project finally profitable.

Copyright, Contributions and Trademark

Who is the copyright owner of PostSharp?

Gael Fraiteur is the sole copyright owner of PostSharp.

How can I contribute to PostSharp?

You are welcome to develop plug-ins based on PostSharp. If some functionalities or extension points are missing, we will gladly add them to PostSharp.

Why don't you accept contributions into PostSharp itself?

Because we don't want to loose code ownership because of small contributions. Holding the whole copyright, we are able to sell commercial licenses. We don't want to loose this ability because of a few percents of contributed code.

Contributors are welcome to write plug-ins that can eventually be packaged together with PostSharp. However, we want to keep a clean separation between code owned by different contributors.

Note that most successful open-source projects rely on private ownership of source code. Collective ownership is rare, even if there are some famous exceptions.

I read PostSharp is a trademark. Can I use the word 'PostSharp' in my plug-in?

Yes, but you have to make it clear that your plug-in is not a part of PostSharp itself, and is not endorsed by the trademark holders. So don't name your product "PostSharp Logging Framework" but "Logging Framework for PostSharp". The same with the namespace: you cannot start of your product with "PostSharp", because it would be misleading.

Comments are closed