What is the IPS file format?
.ips is a patch file that stores byte-level changes for ROM game images. Rather than containing a full game, an .ips file is a binary diff you apply to a legally-owned base ROM to produce a modified version. IPS patches can deliver fan translations, bug fixes, new graphics, music tracks, or language localization packages. The format uses 24-bit addressing, which limits target offsets to 16 MB; for larger ROMs, the community-extended .ips32 format or newer alternatives like .BPS and .UPS are preferred instead.
Applying patches
.ips patch files must be applied using dedicated ROM patching tools. Such a tool will overwrite the given ROM to include the .ips data - or produce a patched copy - and it is advised to keep a backup of the original ROM for safety. Because .ips carries no internal checksum, it cannot verify that it is being applied to the correct ROM version; applying it to the wrong base silently produces a corrupted result. Some emulator software is capable of applying .ips patches on-the-fly, without permanently overwriting the ROM image.
Security & safety
RISK: MEDIUMThe IPS file itself is a passive byte-diff and can't execute, but there are real pitfalls. (1) Legality/source: patches are legitimate, but you must apply them to a ROM you legally own; downloading pre-patched ROMs is piracy. (2) No checksum: applying an IPS to the wrong ROM version silently corrupts the output, so match the exact ROM the patch targets. (3) Fake 'IPS patchers' on ad-heavy sites can bundle PUPs - use the reputable tools listed here (Lunar IPS, Flips, Rom Patcher JS) and keep an unpatched backup of your ROM.
Format details
in a nutshell- Apple iOS panic / crash log - iPhones/iPads write .ips files under Settings > Privacy > Analytics Data - JSON-based panic/crash logs, unrelated to ROM patching.
Programs that open IPS files
Windows2 apps
Lunar IPS (LIPS)
Free Run Lunar IPS, choose 'Apply IPS Patch', select the .ips then your base ROM - it writes the patched ROM.
Rom Patcher JS
Open-source Open the site, drop in the .ips and the ROM, click Apply patch, download the result - runs locally in the browser. 
macOS2 apps
Rom Patcher JS
Open-source Use the web tool (no install) - drop the .ips and ROM, apply, download. Replaces dead native Mac IPS patchers.
MultiPatch
Free Open MultiPatch, choose Apply Patch, select the .ips and ROM (also handles BPS/UPS). 
Linux2 apps
Rom Patcher JS
Open-source Use in any browser; or install Flips (Floating IPS) which also applies/creates IPS and BPS patches.
Flips (Floating IPS)
Open-source flips --apply patch.ips base.rom out.rom (GUI also available); modern successor to Lunar IPS.
Rom Patcher JS
Open-source Browser-based: select patch + ROM, Apply, download - nothing uploaded to a server. Technical details
deep spec| File magic / header | ASCII "PATCH" - 5 bytes (hex 50 41 54 43 48) at offset 0 |
| File terminator | ASCII "EOF" - 3 bytes (hex 45 4F 46) marking end of all patch records |
| Byte order | Big-endian for all multi-byte integers (offsets and lengths) |
| Offset size | 3 bytes (24-bit), addressing up to 16,777,215 bytes in the target file |
| Record structure | {3-byte offset, 2-byte data length, N bytes of replacement data} per patch record |
| RLE encoding | When length field is 0x0000: followed by a 2-byte run count and 1-byte repeat value |
| Integrity / checksum | None - no hash of source or target ROM is stored; wrong base ROM produces silent corruption |
| Compression | No general compression; only record-level RLE for repeated-byte sequences |
| Encoding | Binary with printable ASCII magic strings at header and footer |
| Typical file size | Bytes to a few hundred KB, proportional to the volume of changed data |
| Address space limit | Classic IPS: 16 MB (24-bit); IPS32 variant: 4 GB (32-bit offsets) |
| MIME type | application/octet-stream (informal: application/x-ips-patch) |
| Apply method | Byte-accurate overlay: each record replaces bytes at the exact offset in the target ROM |
| Source ROM verification | Not supported - no CRC, MD5, or SHA hash of the base ROM is embedded in the file |
| Target platform support | Patching tools available for Windows, macOS, Linux, and in-browser (no native OS tie-in) |
| Released | early-mid 1990s (ROM-copier / emulation scene) |
| Latest version | IPS (frozen); IPS32 extension lifts the 16 MB limit; largely superseded by BPS/UPS for larger ROMs |
| Open standard | Yes · royalty-free |
| Specification | zerosoft.zophar.net |
IPS conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about IPS files.
