DOCCHECK

doccheck.j-lab.tools

What did this document hide, and did the hiding work?

Open a released or leaked PDF and DocCheck reports what is inside it: text still readable under the black boxes, text a reader cannot see at all, addresses the file reaches out to, and what it records about its own making. The file is read on your device. There is no upload endpoint.

Open DocCheck How it works

Free. No account. Nothing is stored and nothing is sent.

Sample readout 3 findings

response-batch-03.pdf

412 pages · 4.1 MB · sha256 8f2c…a190

HIGH

Text readable under 6 marks, pages 40 to 97

The mark is a drawn shape. The words are still in the file.

HIGH

Hidden text on page 3

Drawn in invisible mode. Aimed at software, not at you.

INFO

Saved 4 times. Earlier versions are still inside.

An edited PDF keeps its previous revisions.

Illustration of the output shape. Your own file produces your own findings, on your machine.

What it checks

Redaction integrity

For every black mark: is the text still underneath it, was the content genuinely removed, or was the page flattened to an image? It recovers what is recoverable, counts the marks, and measures how much of each page was withheld.

Text you cannot see

Invisible render mode, white on white, sizes too small to read, text parked outside the page. A document carrying text a reader cannot see was written for the software that opens it. DocCheck shows you that text and says why it was hidden.

What the file reaches for

Documents can call home when opened, which tells whoever prepared them that it arrived and when. DocCheck resolves none of those references and lists every one of them, along with anything embedded that would run.

What the file records about itself

Producer, creator, creation and modification times, and how many times the file was saved. An edited PDF keeps its earlier revisions inside it. These are observations, not accusations: what they mean is your call.

Why there is no upload

The architecture is the promise

Your file is read by code running in your browser. It is never transmitted.
This page declares that it may not open a network connection at all, so the browser itself enforces it. Open your network tab and watch: analysing a document produces no requests.
No account, no session, no log. There is no server that holds documents, so there is nothing to subpoena and nothing to breach.
No language model reads your document. Sending a received document to any outside service is the exact risk this tool exists to remove.

What it does not do

It never says a document is genuine or forged. It reports what the file contains and you judge it.
A failed redaction is evidence of a leak, not evidence of intent. DocCheck does not tell you why.
A scanned page has no text layer, so nothing can be recovered from under a mark: there is nothing there. DocCheck says so instead of reporting the page as clean.
This release reads born-digital PDF. Word and Excel files arrive next.