[ Docs ](https://sendnda.com/docs)     

 [ Evidence ](https://sendnda.com/docs/evidence)     

Verify a copy
=============

Upload a PDF and see whether it is, byte for byte, the one both parties signed.

 03

Evidence
--------

Article 3 of 3

 Someone sends you a PDF and says it's the NDA you both signed. The [verify page](https://sendnda.com/verify) tells you whether it is, byte for byte, the PDF Send NDA sealed. It's free and needs no account.

How to check
------------

1. Open the [verify page](https://sendnda.com/verify).
2. Drop the PDF on it, or click to pick the file. It has to be a PDF of 20 MB or less.
3. Press **Verify PDF**.

The answer is one of two: the file matches an NDA sealed on a given date and time, or it matches none.

What a match means
------------------

Send NDA takes the SHA-256 of the file you uploaded and looks for a sealed PDF with the same hash. Finding one isn't enough on its own. It then checks that NDA's whole [signing record](https://sendnda.com/docs/evidence/the-signing-record), event by event. You only see a match when both hold:

- the file's SHA-256 equals the one recorded when the PDF was sealed;
- the chain of events behind that NDA passes every check.

A match says the file is the one both parties received at completion, and that the record of how it came about is intact. It doesn't say the agreement is enforceable, or that it applies to the situation you have in mind. That's for you and, where it matters, your lawyer.

Why a real copy can fail
------------------------

The check compares exact bytes. Any change makes the hash different, including changes that leave the text looking identical:

- printing the PDF to a new PDF, or saving it again from a viewer;
- adding a comment, a highlight or a signature on top;
- compressing it, or running it through a scanner;
- a PDF from before completion, which was never sealed.

If a copy fails, ask for the file exactly as it arrived by email, or download it again from your own signing link. Both are the sealed original.

What happens to your file
-------------------------

Your upload is hashed, compared and then deleted, whether it matches or not. Nothing about it is kept, and the check isn't written to the NDA's signing record. To stop anyone trying hashes at scale, the page allows 10 checks per minute from one IP address; past that, you're asked to wait a minute.

 Checked against the code on 21 September 2026.

 [   The sealed PDF ](https://sendnda.com/docs/evidence/the-sealed-pdf)