Verify a ROM with checksums
Calculate CRC32, MD5 and SHA-1 for any file and compare them against the value a patch author published. Matching hashes mean you have the exact ROM the patch expects. Hashing runs on your device, so nothing is uploaded.
What this checksum tool does
It calculates CRC32, MD5 and SHA-1 for any file you give it, several at once if you like. The usual reason to want that is to confirm a ROM is the exact file a patch expects, before you discover otherwise the hard way.
Hashing runs in a background thread on your own device, so large files do not freeze the page and nothing is uploaded.
CRC32, MD5 or SHA-1?
| Hash | Length | Where you see it |
|---|---|---|
| CRC32 | 8 hex characters | Romhack readmes, No-Intro DAT files, .sfv files |
| MD5 | 32 hex characters | Patch documentation, redump records |
| SHA-1 | 40 hex characters | No-Intro and redump databases |
Any of them confirms file identity. CRC32 is what romhack authors quote most often because it is short. SHA-1 is what preservation databases publish.
Comparing against an expected value
Paste the checksum from a readme into the compare box and each file is marked as matching or not. You can also load a .sfv, .md5 or .sha1 file and every entry in it gets checked at once.
A mismatch usually means a copier header, a different region or revision, or an already-patched ROM rather than a corrupt download. Verifying a ROM covers how to tell them apart.
Frequently asked questions
How do I check a ROM’s CRC32?
Drop the file into the tool above. CRC32, MD5 and SHA-1 are all calculated on your device and shown together. Compare the CRC32 against the value in the patch author’s readme or a No-Intro database entry.
Which checksum should I compare against?
Whichever one the source you are checking against publishes. Romhack readmes usually quote CRC32, while No-Intro and redump publish SHA-1. Any of them confirms the file is identical.
My ROM’s checksum does not match. What does that mean?
Usually a copier header, a different regional release or revision, or a ROM that has already been patched. A genuinely corrupt download is less common than any of those. Hashing the zip rather than the ROM inside it is another frequent cause.
Can I check several files at once?
Yes. Select or drop as many files as you like and each is hashed in turn. You can also load a .sfv, .md5 or .sha1 manifest and every entry in it will be matched against the files you add.
Are my files uploaded to check a checksum?
No. Hashing runs in a Web Worker on your own device. Nothing is transmitted, and the tool keeps working if you disconnect from the internet after the page loads.
Is MD5 still safe for verifying ROMs?
For confirming that a file matches a known one, yes. MD5 is unsuitable for security purposes because collisions can be constructed deliberately, but that is irrelevant when checking a download against a published hash.