There's enough legal uncertainty about API calls being considered linking that it keeps coming up. Minio are probably at the forefront of claiming this somewhat implicitly while referring you to your lawyer (or their pricing page, preferably) when asked about how they understand the AGPL.

FSF/GNU have an example of an AGPL proxy becoming compliant by serving it a page with the offer to download source code on the first request, pretty far off from reality if you ask me. That's also the big other issue, AGPL is unclear about conveyance over a network. Does a header work? Does a link to the source repo work or do you need to offer hard copies? What do you do if the "networking" is a highly specific protocol that simply can't make that offer over the wire?

I much prefer the clarity of intent of the EUPL.

Nah, the AGPL is pretty clear (and way clearer than the GPL and LGPL due to combined/derived work fuzziness). The issue with it isn't anything to do with the mechanism of the license itself, because it is pretty clear what the criteria are (and offering an API over the network definitively constitutes Remote Network Interaction) and how you can fulfill the source distribution. The real issue is that the AGPLv3 doesn't preclude a third party from commercializing the software (whether modified or not).

The problem with Minio is how many layers of indirection "interacting with an API" consitutes. If I write a webapp that uses Minio in the background, Minio has stated that their belief is that your webapp is subject to the viral part of the AGPL.

That's interesting. I was reading their licensing compliance FAQ at https://min.io/compliance and it doesn't allude to that; in fact it suggests that for instance calling a REST API doesn't imply derived work (modulo the specificity piece), referencing the GPL. The omission of the over-the-network AGPL provision is notable. I wonder if it's obscure on purpose?

Perhaps even stranger, MinIO have publicly stated they have revoked an Apache 2 license grant to a third party, Weka: https://blog.min.io/weka-violates-minios-open-source-license...

Not sure what their counsel is thinking there..

MinIO has taken (and still is taking) contributions without CLA, so they likely don't even have the ability to sell license exceptions.

AGPL doesn't forbid Amazon from providing a competitive service using the software. Elastic License/SSPL/BSL all do. That's the difference.

It also ensures Amazon can’t add any secret sauce to the code they offer - everything must remain open.

Well, the comment from OP isn't necessarily complete. The AGPL is not about preventing someone from using source code (indeed that would be contrary to the spirit of all liberal and copyleft licenses), but rather the condition under which source code modifications need to be made available.

Specifically, if you offer the software for "Remote Network Interaction" (AGPLv3 section 13), well, "if you modify the Program, your modified version must prominently offer all users interacting with it remotely through a computer network (if your version supports such interaction) an opportunity to receive the Corresponding Source of your version".

I think the original challenge with AGPLv3 vs (to grossly generalize) the VC-backed open source corporate ecosystem was not around source code, but around monetization as SaaS by the hyperscalers. The problem there is even if the hyperscalers publish source code modifications (which they probably have no problem with) they have such sales efficiency and gravitational pull that they will end up eating your business.

translation: AWS refuses to provide unmodified open source hosted software as a service or to open source the changes they make to host it.

It's not a "can't" it's a "won't".

AWS at the time had AGPL on its list of licenses that couldn’t be used. There were other clouds in China especially ignoring the AGPL provisions and I think SSPL was used to try and be more explicit.