.NET Foundation Statement on Open Source Maintenance Fees | .NET Foundation

The .NET Foundation exists to support a healthy, commercially friendly, open-source ecosystem around the .NET platform. We believe two things can be true at the same time: maintainers need sustainable ways to support the work required to keep open-source projects healthy, and consumers need clear, predictable terms when adopting open-source software.<br>Some open-source projects have adopted or are considering the Open Source Maintenance Fee (OSMF) and similar funding mechanisms. These models generally distinguish between source code made available under an open-source license and maintainer-provided binary releases, package-manager artifacts, release services, support channels, project infrastructure, or other project conveniences.<br>The .NET Foundation does not take a position for or against the use of OSMF or similar funding models, whether by projects inside or outside the Foundation. Different projects have different sustainability needs, and organizations that consume open-source software should evaluate each project's terms in the context of their own legal, procurement, security, compliance, and supply chain requirements.<br>Guidance for Consumers<br>Our guidance for consumers of .NET open-source software is straightforward: do not assume that software obtained through a package manager is governed only by the source repository's license file.<br>Before adopting or upgrading dependencies, consumers should review the applicable source license, package metadata, package license expression, README, notices, EULAs, release terms, and any project-specific funding, access, or use requirements. Consumers should also distinguish between rights granted in source code under an open-source license and additional terms that some maintainers may apply to maintainer-provided binaries, hosted services, release channels, project infrastructure, support, or other convenience artifacts. Where those terms are unclear, consumers should consult their own counsel.<br>This guidance applies to all .NET open source projects, whether Foundation members or not. Foundation membership provides certain structural assurances described below, but does not eliminate the consumer's responsibility to review the specific terms applicable to the artifacts they consume.<br>Foundation Projects and Existing Eligibility Criteria<br>Foundation projects remain subject to the Foundation's existing eligibility criteria, which include, among other things:<br>Source code is distributed to the public at no charge under a Foundation-approved permissive open source license.

Mandatory dependencies of the project are offered under a standard, permissive open source license approved by the Foundation, with limited exceptions for platform or hardware-specific libraries where no alternative is available.

A build script exists that can produce deployable artifacts functionally equivalent to the official releases, with the exception of code signing.

Committers are bound by a Contributor License Agreement, copyright ownership is clearly defined, and the project adheres to the .NET Foundation Code of Conduct.

These criteria continue to apply, and they meaningfully bound the design space available to Foundation projects considering OSMF or similar funding models.<br>A funding model that is incompatible with these criteria — for example, one that paywalls source code, restricts the public's ability to build equivalent artifacts from source, or introduces a mandatory dependency under non-permissive or paid terms — would put a project's eligibility in question.<br>A funding model that applies only to maintainer-provided binaries, hosted services, support, signed releases, official package distribution, or other convenience artifacts, while leaving the source and self-build path intact and the mandatory dependency chain permissively licensed, is generally compatible with these criteria. Adopting such a model does not, by itself, violate Foundation policies.<br>The Foundation's interest is not in approving or denying specific funding model decisions, but in ensuring the ecosystem has clear and consistent information about the terms under which Foundation projects are distributed. Maintainers considering material funding-model changes — including the introduction of OSMF, EULAs on official packages, payment requirements for binary distribution, or similar changes — are encouraged to notify the Foundation in advance so that consumer-facing communications and ecosystem coordination can be handled clearly.<br>Supporting Maintainers<br>The Foundation encourages organizations that benefit from open source software to support the maintainers and projects they rely on. Sponsorships, paid support, consulting, commercial services, dual licensing, commercial editions, maintenance fee models, and other sustainability approaches can all play valuable roles in the ecosystem when they are clear, transparent, and compatible with the...