DocSupra › Integrity Scanner › PDF changed after signing · Español
How to check whether a PDF was changed after it was signed.
The short answer. Drop the signed PDF into the Integrity Scanner. A digital signature covers the bytes that existed when it was applied; anything saved afterwards is appended after it. The scanner lists each signature, what was added after it (page text, notes, form values, another signature), and whether the signed bytes still match the digest stored inside the signature. It states facts about the file; it does not validate the signer’s certificate or identity.
Most PDF editors do not rewrite a signed file: they add the change at the end and keep the original underneath. That is good news for you, because the file carries its own history. The scanner reads it on your device and writes what happened in plain words.
What it reads in the file
Who the signature field names, when it was applied according to the file, and which part of the file it covers.
Every revision saved after each signature and what it changed: page text, annotations, form values, or a further signature.
Whether the bytes the signature covers still match the digest stored inside it. If they do not, the signed content itself was altered.
A signed PDF printed to a new file or flattened loses the signature record. The scanner says that the copy carries no digital signature, instead of guessing.
When the signed version is still inside the file, download it byte for byte to keep the copy that was actually signed.
A PDF report with the SHA-256, the level (Low, Medium or High) and the technical fact behind each reason, dated.
How to check a signed PDF
Open the Integrity Scanner
Go to docsupra.com/?abre=scanner. Nothing is installed.
Drop the signed PDF
Up to 40 MB; a folder or a ZIP if you have several. The file is read on your device.
Read the three answers
Edited? says whether anything was saved after the signature; Source and time names the software and dates; Safe to open? reports scripts and executables.
Open the signature detail
Each signature, what was added after it and the digest result. Export the PDF report and keep it with the file.
What it cannot tell you
Who really signed. The scanner does not validate certificates, trust chains or identities; a valid digest proves that the signed bytes are intact, not that the named person is who they say. It cannot recover a signature from a flattened or printed copy, and a scanned handwritten signature is an image, not a digital signature. For a legal question, take the report to whoever decides it.
What the Integrity Scanner costs
From one lease to a whole department: pay once for a few checks, or subscribe.
Document downloads are not part of this subscription: repairing and exporting documents is the Compliance Studio. Prices are in USD and exclude any tax that applies in your country; Stripe calculates it and shows it before you pay.
Check a signed PDF now →Questions
The PDF shows a green check in my viewer. Is that enough?
A viewer’s check usually means the signed bytes are intact. It does not show what was added afterwards: a later revision can sit on top of a valid signature. The scanner lists those later revisions and what they changed.
Can something be added to a signed PDF without breaking the signature?
Yes. Incremental saves append content after the signature without touching the signed bytes, so the signature stays valid while the visible document changes. That is exactly what the scanner reports.
What if the signature is just an image of a handwritten one?
Then there is no digital signature to check. The scanner says so, and still reports the file’s revisions, software and dates.
Is my PDF uploaded to a server?
No. The file is read on your own device, inside the browser. There is no upload endpoint, no server copy and no retention period. Once the page and its engine have loaded you can disconnect from the internet and it still reads the file and shows the result; downloading a paid result needs a connection for the licence check, which sends a count and never the file.
What does it cost?
Where the file came from and whether it is safe to open are shown to everyone. Whether it was edited, how, and what it exposes comes with a check: 3 checks with the $9.99 pack, 50 with the $19.99 pass, or up to 1,000 files a month with the $14.99 subscription. It is included with Professional Team and Corporate Studio.
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