Apache 2 library inclusion into Stan Math--general policy case. Trip wire consensus decision

We will allow Apache 2 license dependencies into Stan Math which is itself new BSD license. This impacts GPL2 licensed projects.

This is a trip wire consensus decision. Any reasonable objection shared in this thread by midnight September 14th anywhere on the planet will ‘trip’ a review, otherwise the proposal will be adopted. Description of the experimental trip wire process is at the post designated by: Licenses of dependencies

Extensive discussion of the proposal at the thread: Licenses of dependencies


Walker issue raised, please clarify if needed.:


Please edit the second sentence to say “This impacts GPL2 licensed projects.”

It does not impact GPL3 license projects (including those under the stan-dev GitHub repo) and does not impact projects that compile Stan programs at runtime (like brms, TMBstan, etc.)

Done and thanks for catching it.

Text is still the same

Not on the issue over at Walker ;). Fixed here too now.

Thanks for the notification. As GPL3 seems to be Apache2 compatible, I think I can just switch walker to that instead of GPL (≥ 2).

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So are we there now?

Deadline is well over. I haven’t heard any objections against the Apache 2.0 license.

Thus, I would assume we are good unless I have overlooked anything.


The week has passed and no one objected. We’re now able to include Apache 2 licenses in Stan :)