[celdon25]

A good compromise that would keep things equal for everyone would be to use a strong copyleft license (GPL). Normally when I think of specific scenarios involving companies using it (a real issue that has come up for me before), GPL was strongly considered as an option. Not to prevent them from using it, but rather to ensure that they don't use the free software to gain a further advantage without giving their own improvements to that same software back to the community.

[cimmanom]

GPL only requires them to contribute their changes if they distribute a version of the software with those changes. The AGPL defines distribution to include hosting SaaS, but that may not be applicable to whatever the OP has written.

[celdon25]

True, I have been trying to steer clear of the "centralize everything on our servers" trend in tech lately so I keep forgetting about that one...