Corrupted save after Hex editor

[XD_Lele]

Every time I edit my save in the hex editor, I need to put it in pkhex and save it before injecting it into the game. If I don't do this, the save shows as corrupt. Why does this happen? What does pkhex do and can I do it manually? Can I apply it to other games?

[Kaphotics]

https://en.wikipedia.org/wiki/Checksum

[XD_Lele]

2 hours ago, Kaphotics said:

https://en.wikipedia.org/wiki/Checksum

any program or method to identify which algorithm to use?

[Kaphotics]

59 minutes ago, XD_Lele said:

any program or method to identify which algorithm to use?

Refer to PKHeX's source code, because the checksum algorithm and region it verifies depends on which game the save file is for.