Discontinued in protest of Google's new draconian Android APIs and policies. Android R (11) will break my apps by leaving files completely inaccessible through standard means, and the effort it would take to update them to use the new APIs is too much. I can no longer consider Android a real OS if R releases with its currently proposed changes. I will delist this app on February 1, 2020. It will still be accessible to those who have purchased it, but I cannot guarantee it will continue to work on any given new Android version.
The source is and has been available here (sans golden icon): https://github.com/xperia64/android-rom-patcher




Purchase ROM Patcher (Donation) to support future development and enable the use of NMP patches


ROM Patcher is a ROM/binary file patcher that supports IPS, IPS32, UPS, BPS, PPF, XDELTA1, XDELTA3, DPS, ASM, XPC, DLDI, APS (both GBA and N64), NMP, and BSDIFF patch types. It also supports decompressing ECM files via unecm. Simply choose a file to patch, the patch itself, and optionally an output file name and tap "Patch".