[josephcsible]

Any license that prohibits selling a hosted version will necessarily fail to meet the Open Source Definition. Your best bet would instead be to pick a license that the companies that would do so are irrationally afraid of. The AGPLv3 is the usual choice for this. Even though, e.g., GCP would be legally allowed to, Google internally has an absolute policy against doing so: https://opensource.google/documentation/reference/using/agpl...

[xyzzy_plugh]

AGPL is certainly the popular choice but it is particularly difficult to wield properly in a corporate environment like GCP or AWS. If your goal is "ha ha fuck you megacorp good luck using THIS license" then congratulations, AGPL is for you. If your goal is to foster a community and ensure service providers contribute upstream, then AGPL fails to meet that bar as it is far too hostile for big businesses.

[josephcsible]

Proprietary licenses are way more hostile than any FOSS license, though.