Overview

The Microsoft Reference Source License (MS-RSL) is the most restrictive of the Microsoft source code licenses. The license prohibits all use of source code other than the viewing of the code for reference purposes. The intent of this license is to enable licensors to release, for review purposes only, more sensitive intellectual property assets.

Microsoft commonly uses this license for developer libraries where modification is not required to make use of the source code. In these cases, the importance of transparency is based on the need for developers to more deeply understand the inner workings of the source code. In doing so, the licensees will be more effective in writing software that makes use of the licensed source code.

The copyright and patent grants in this license are both royalty free, meaning that the licensee does not have to pay anything to the licensor to make use of the source code. The license limits the source code release to use on the Windows platform only. Microsoft cannot provide legal advice on the use or implications of this license. We recommend that developers obtain appropriate legal advice before deciding how to license their source code.

The source code for the .NET Framework libraries are released under a modified Microsoft Reference Source License.

Terms of Use

Developers who wish to access source code under the Reference Source Program must agree to the license that accompanies the code.
Licensees may use the source code to assist with the development of commercially distributed products.
Licensees may not modify or redistribute the source code.

Eligibility Requirements

There are no eligibility requirements for this program. Everyone who agrees to the accompanying license may use the source code provided under the Reference Source Program.