The most secure and direct way to flash an IPSW is through official Apple software on a computer.
When looking for software that handles firmware flashing, "free" can sometimes mean "risky." It is vital to stick to reputable tools that have stood the test of time. Here are the best options available today. ipsw flash tool free
Free Compatibility: Windows / macOS
Tenorshare ReiBoot is a commercial product, but its free tier allows you to flash a standard IPSW. The catch? You cannot use their "Repair Operating System" feature for free (that fixes boot loops without data loss). However, the standard "Restore/Flash" button remains free and functional. The most secure and direct way to flash
If 3uTools fails, try .