Most games use checksums to validate if a save has been altered or not. Checksums are values calculated by making more or less complex operations on all the data in the save file.
When you load your save, the game will calculate the checksum and compare with what it saved previously. If the result is the same, the save can be loaded, otherwise, it is indicated as corrupted and depending on the game, the save can be deleted.
The tools present on the site recalculate the checksums every time you save, even if you don't edit anything, which can repair your save if it is corrupted.
In most cases, yes.
Save editors can detect the format of a save file and adapt the values to allow the edition.
If you are in possession of a save file that is not recognized by the tools, you can contact me on Discord or at contact@game-tools-collection.com .
PSP save files are encrypted by default when exported from a PSP or generated with PPSSPP. You need to decrypt your save in order to edit it.
If you're save has been generated with PPSSPP, follow those steps:
Open the memstick folder (on the root of the PPSSPP folder by default).
Navigate to PSP > SYSTEM, then open the ppsspp.ini file in a text editor.
You should find a EncryptSave = True line. Replace True by False then save and quit.
Now launch your game on PPSSPP, open you save and save again.
Now your save should be decrypted.