In addition to IPSW files, 3uTools also saves SHSH blobs and cached firmware data. These are typically stored in a cache folder within the 3uTools installation directory. According to an official tutorial:
If your local C: drive is running low on space, you can redirect future firmware downloads to an external hard drive, secondary SSD, or custom partition: 3utools ipsw location top
Always ensure that your IPSW files are not corrupted. 3uTools might provide options to verify the integrity of IPSW files. In addition to IPSW files, 3uTools also saves
C:\Users\YOUR_USERNAME\AppData\Roaming\3uTools\Downloads\Firmwares 3uTools might provide options to verify the integrity
Click the icon (represented by a downward-facing arrow) located in the upper right-hand corner of the program window. Locate the Downloads management screen.
Browse your computer, select the manually downloaded .ipsw file, and click . Essential Storage Maintenance & Firmware Tips
Press the on your keyboard to open the Run dialog box.