Check a PDF · Before You Trust It
Got an invoice, bank statement, payslip, quote or contract as a PDF? See how the file was made and changed: earlier versions saved inside it, edits after signing, text painted over, numbers set in a different font, disguised links and IBANs with wrong check digits.
Saved versions
Each later save was appended to the file. Download an earlier version to see the document as it was then.
How to check a PDF
- Drop the PDF onto the box above. The check starts by itself.
- Read the three lists: Facts read straight from the file, things worth a closer look, and things that are normal but mentioned for completeness. Click a finding to see where it is on the page.
- If the file holds earlier versions, see what changed in each one or download it. Save the findings as a PDF report or CSV.
What it looks at
Earlier versions. Many programs save a change by appending it to the end of the file, so the version before it is still inside. The check extracts every version and shows exactly which words, pages and form fields changed in each save.
Signatures. A digital signature only covers the file as it was when it was signed. The check shows whether anything was saved afterwards, and whether that was only signature data such as timestamps, filled-in form fields, or real changes to the pages. It does not validate the certificate; a reader such as Adobe Acrobat Reader does that.
Painted-over text. A common way to change an amount or a date is to cover it with a white box or a picture and type a new value on top. The old text stays in the file. The check finds text that is in the file but cannot be seen, including blacked-out text that was never really removed.
Fonts and positions. A number typed in afterwards often ends up in a slightly different font or size, or a fraction of a point off the line. The check compares each number with the others on the same line, not with the whole page, so headings and bold totals don't count.
Links and bank details. Every web link is listed, and links whose visible text shows one address while they open another are flagged. IBANs are checked against their check digits, which catches typos and many hand edits.
Properties. The program that made the file, the one that last wrote it, dates that contradict each other, attached files and scripts. Printers and report generators are treated as normal; only real PDF editors are worth a mention.
What it cannot do
A careful forger who rebuilds a document from scratch leaves none of these traces, and text changed directly with a PDF editor and saved as a completely new file may leave little more than the editor's name. A perfectly genuine document can also trigger several of them. Treat the results as reasons to ask questions, not as a verdict. Call the company using a number you already know before you pay a changed invoice.
Frequently asked questions
Can this prove a PDF is fake?
No tool can, from the file alone. It tells you how the file was made and changed, and what is worth asking about.
Why does it say my genuine document was saved several times?
Signing, form filling, comments and some programs all add a version. The check tells you what each save changed, and saves that only add signature data are listed as normal.
Is my document uploaded?
No. Everything runs in your browser tab. There is no upload and no account.