The client folder holds contract_final.pdf, contract_final_v2.pdf and contract_signed_client.pdf. Which one was approved? Is the one that came back signed exactly the one you sent? Or did someone "take the chance" to tweak a comma before signing?
This question comes up all the time in law firms, legal departments and anywhere documents travel by email. The good news: you can answer it with certainty in seconds.
Name, size and date prove nothing
It's tempting to go by what your computer shows, but none of these signals is reliable:
- Name — the same file can have different names, and different files can share a name;
- Size — two documents with one word swapped can have exactly the same size;
- Modified date — it changes when you copy, download again or sync with the cloud, even with no change to the content.
What settles it is comparing the entire content, byte by byte. And the practical way to do that is with the file's fingerprint.
A file's fingerprint (hash)
A SHA-256 hash is a 64-character code calculated from the whole content of the file. It has two properties that matter here:
- Identical files always produce the same hash — regardless of name, folder or date;
- Any change, however small, produces a completely different hash — a single comma is enough.
That's why two files with the same hash are, in practice, the same file. We explain the concept in more detail in what is a SHA-256 hash.
How to check in RoseLab in seconds
- Open Verify integrity;
- Select or drag two or more files at once;
- The tool calculates each fingerprint and answers right away:
- "The files are identical" — the content is exactly the same, bit for bit;
- "The files are different" — and if some of them match each other, it shows which ones.
It works with any file type: PDF, Word, spreadsheets, images, videos. And, like the other RoseLab tools, the calculation happens in your browser — the files aren't sent anywhere.
Got the hash by email or in a report instead of the file? Use the Paste button to check whether your file matches that code.
Situations where this solves the problem
- Signed version vs approved version — before filing, confirm that the PDF that came back signed is the one you sent;
- Duplicate files — find out which copies scattered across folders and emails are truly the same before deleting any;
- Backups — check that the file copied to an external drive or the cloud arrived intact;
- Proof that nothing changed — a hash recorded today lets you prove, months later, that the file is still the same.
And when the files are different?
The hash tells you whether something changed, not what. When the result is "different" and you need to know exactly which passages were altered, open both PDFs in the PDF comparison tool: it highlights what was removed and what was added, page by page. For long documents, see how to compare PDFs with many pages.
One important detail: a PDF that was saved again can have the same text and still produce a different hash, because the software updates internal information (such as the modification date). In those cases, Verify will say "different" — and the comparison tool will show that the content is still the same. The two tools complement each other: one answers "is this exactly the same file?", the other answers "what changed in the text?".
Ready to put it into practice?
Free, no sign-up — and your files never leave your computer.
Check my files