Any backend that can spit out html fragments should works. The backend doesn't have to be aware of htmx. Heck, the response doesn't have to be a fragment either

Any backend that can spit out html fragments should works. The backend doesn't have to be aware of htmx. Heck, the response doesn't have to be a fragment either because you can just select which part of the response to update the dom with using the hx-select attribute.