Square’s terms of service forbid use of AGPL-licensed software in online stores

So, then, since Square’s application is a work, if an AGPL service interacts with it to modify Square’s work, your assertion is that this does not count as a modification introducing AGPL responsibilities.

That’s useful to consider, but it doesn’t reassure me enough to remove the risk altogether. I would, if I were a coder in Square’s position, acknowledge this explanation and then very likely still move to deny AGPL interactions as a whole rather than try to finesse the exact legality as described. I care a lot about licensing but I also want to get work done without fear of AGPL lawsuits.

I am not a lawyer - However my own take on the AGPL is that if there's an external tool, an entirely separate process that is open source and does things, then as long as that source code is published and public a user is OK to use AGPL things.

As an example, let's say that I have a game. That game happens to want to have a way of rendering some HTML content for printing / making a PDF. It's OK to ship an open source thing with your game, like a hypothetical FrozenFluff web-browser licensed in AGPL. There are two distinct entities there: a FF binary that gets called with a file to render (which is AGPL and an AGPL processed result that is under the copyright of whomever's material was rendered) and another distinct binary the GameX that happened to call an external process.

The line to cross there is that the AGPL stuff can't be linked against your own program. I'm even more unsure how a module might or might not be licensed. I think since that's an addin then the code for the module (including headers) would have to be AGPL compatible and released, but that the rest could probably be closed.

This line is less clear when it comes to websites however. I think the best equivalent would be to make a wrapper interface that is AGPL licensed, published, and links to/calls the AGPL software. It should have a distinct URL. That URL might only be on the localhost (for security) and would hand back whatever results exist. The proprietary interface could talk to that URL and get results.

> I am not a lawyer - However my own take on the AGPL is that...

I am also not a lawyer, however my take on many legal things is that it doesn't matter what my take is, or even if courts will agree with my take, what matters is whether the benefit is worth the hassle if I end up needing a lawyer to deal with it.

Even if you "win," the engagement with lawyers can cost you so much that it becomes a pyrrhic victory, and the amount of time required to deal with certain legal squabbles is astounding.

So sometimes, the right thing to do is to shy clear of anything that carries with it some risk of legal potholes.

> If the third party sold a copy of MS Windows using Square's services/software/platform, could Square even in theory be sued by Microsoft for copyright infringement?

If Square was knowingly engaged in the distribution of Microsoft's software against Microsoft's license terms, absolutely. (EDIT: Well, I'm assuming they're helping distribute it, might be "conspiracy to commit copyright infringement" otherwise?)

> So AGPL isn't something special.

Correct...ish. I'm sure piracy, if not explicitly against the ToS, will get you kicked off too. The closest the AGPL gets to being special is the nebulous situation we find debated throughout this HN discussion tree - is it legal for Square to distribute? It's reasonable that customers might think so. It's reasonable that square's lawyers might think not.

But you've pointed out that even that isn't unique to the AGPLv3 specifically - so why call it out, specifically? My wild uneducated guess - a customer used AGPLv3 software, Square became aware of it somehow (license review team? or perhaps someone tried to exercise AGPLv3 rights and requested server code?), and eventually involves their Lawyer. Lawyer then looks into the specific case of their customer using specific software, reads the license of said software (AGPLv3), and becomes nervous about Square's possible legal exposure.

After the awkward conversation with their customer (possibly much like the discussion in this HN thread as to if Square would/wouldn't be knowingly facilitating AGPLv3 license violations by not sharing their own code, and thus legally liable), Square settles the matter by banning the specific license outright, possibly after giving them a chance to move away from AGPLv3 software first since it wasn't strictly against the ToS, and then explicitly adds it to the ban list for the benifit of customers and customer service who probably weren't privy to whatever lengthy private discussions might've been had with that one specific customer.

That's your interpretation and that's the problem because you might be wrong in some subtle way that a lawyer could exploit. Also, you are looking at a single paragraph, there's a lot more to this and it includes notions of linking, derivative works, distribution, etc. Lawyers really don't like having a lot of open questions around this stuff and some of the more extreme interpretations would be very disruptive for any business that wants to keep parts of their software proprietary.

The other point is that the intention of this license is explicitly to prevent people commercializing software licensed this way through proprietary extensions, additions, etc. The whole point of the license is to make that difficult/impossible. If you use AGPL software, you have to respect this intention.

Gplv3 is also not that popular with legal departments for the same reason. Even Gplv2 is generally frowned upon but better understood since there is a fair bit of case law around it and known ways of dealing with it when e.g. shipping binary kernel modules with an OS, which is one of those legally grey areas where you have to depend on legal interpretations of the license. Gplv3 was explicitly written to close some of those loopholes in Gplv2: they were unintentional.

So, this is not FUD but basically lawyers doing their jobs and they are fairly consistent in their reservations with respect to this license across the industry. You talk to lawyers in any fortune 500 company and they'll probably will be very reluctant to sign off on any AGPL dependencies.