Keepass 1 is .NET Framework based. Keepass 2 is .NET Framework and has a Mono build of varying success. 1 and 2 are the originals and still actively developed.

Keepass 1 is .NET Framework based. Keepass 2 is .NET Framework and has a Mono build of varying success. 1 and 2 are the originals and still actively developed. KeepassX has stalled development since 2016 but was a true cross platform desktop client KeepassXC is the fork of X and at this point in time is lightyears ahead of X. I'm sure the developers of XC may have wanted to contribute to X but X seems to have been spearheaded by a single developer who stalled on letting other devs become maintainers. So the community forked it. But to answer the question, it's impossible to merge X and the original because their code bases are in entirely different languages and arguably X doesn't give you anything than the one man dev show.