Blackline Open the tool

Redaction guides

Four short, practical pages about getting information out of a document rather than hiding it under a rectangle. Every one of them ends with a test you can run on your own file.

Why redacted PDFs leak: how a black box gives the text back

What the rectangle actually is inside the file, the five ways the text comes back out, why blur and pixelation are worse than useless, and the one-command test.

How to redact a PDF for free, without uploading it anywhere

What Preview, Word, print-to-PDF, LibreOffice and the free online converters really do to your file — a route-by-route table, and how to verify the result.

How to remove PDF and image metadata before you send a file

Author, original filename, GPS, timestamps, embedded thumbnails and earlier revisions — how to read them, remove them, and confirm they are gone.

Document redaction checklist for GDPR, HIPAA and disclosure

A pre-release checklist: what must be removed, what is not on the page, how to verify, what to record, and why the tool's chain of custody matters.

Open Blackline — free, runs offline, nothing uploaded