The most reliable way to edit save files is to use a File Decoder/Encoder or a dedicated Desktop App .
The offline experience is slightly rougher around the edges than the "click and upload" web experience, but for privacy, speed, and ad-free usage, it is the superior choice for dedicated RPG Maker fans.
If a save editor fails or the encryption is too heavy, is the ultimate offline alternative. It does not edit the save file directly but edits the RAM while the game is running.
Even with the best tool, mistakes happen. Here are the top three issues and fixes.
Enter the .