Comment by paxys
I dug around for ~10 minutes and it's probably not an exaggeration to say that Mattermost might have the most confusing licensing of any software product in existence.
From the license page on their repo (https://github.com/mattermost/mattermost/blob/master/LICENSE...):
> 1. You are licensed to use compiled versions of the Mattermost platform produced by Mattermost, Inc. under an MIT LICENSE
So just the compiled versions, not the source code. Ok, at least that is clear. But - the MIT license explictly allows for modification and redistribution. So can I do that?
The next line.
> See MIT-COMPILED-LICENSE.md included in compiled versions for details
Except this file doesn't exist anywhere in the repo or outside.
> You may be licensed to use source code to create compiled versions not produced by Mattermost, Inc. in one of two ways:
> 1. Under the Free Software Foundation’s GNU AGPL v3.0, subject to the exceptions outlined in this policy; or > 2. Under a commercial license available from Mattermost, Inc. by contacting commercial@mattermost.com
What does "may be licensed" mean? Do I have to contact them for a license? Or is an AGPL license implied?
> You are licensed to use the source code in Admin Tools and Configuration Files (server/templates/, server/i18n/, server/public/, webapp/ and all subdirectories thereof) under the Apache License v2.0.
Sure, let's throw another license in there, because there weren't enough already.
> We promise that we will not enforce the copyleft provisions in AGPL v3.0 against you if your application ... [set of conditions]
WTF does a "promise" mean here? Is this actually AGPL or not?
Then they have copy pasted the entire Apache License, even though the project isn't licensed under Apache. Why??
Oh but that's not all.
There's a separate license page at https://docs.mattermost.com/product-overview/faq-license.htm..., which says:
> Mattermost Team Edition (Open Source) - Open Source MIT License.
Uh, what? That goes against everything said in LICENSE.txt. So now we are back to fully open source?
Wouldn't that license also violate the AGPL? I mean, it does say, in section 7:
> All other non-permissive additional terms are considered "further restrictions" within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term. If a license document contains a further restriction but permits relicensing or conveying
So, my interpretation is that I am free to license it under the AGPL; there is no "well, we might decide to do that", and I can strip all conditions they place upon me and comply only with the AGPL, and legally there is nothing they can do about it.