Guides & tips for working with PDFs
Practical how-tos, behind-the-scenes notes, and product updates from the team behind Blackpdf.
Security
Protect, unlock, redact, and sign PDFs.
How to Password-Protect a PDF Before Emailing It
Sending something confidential by email? Here's how to encrypt the PDF first — and the step most people get wrong: how to share the password safely.
Why Blacking Out Text in a PDF Doesn't Work
Drawing a black box over sensitive text hides it visually but leaves the data in the file — anyone can copy it straight out. Here's why, and what actually removes it.
How to Remove Personal Information (PII) from a PDF
Strip emails, phone numbers, SSNs, card numbers, dates, and IP addresses from a document before you share it — using auto-detection to catch what you'd miss by eye.
How to Create an Electronic Signature You Can Reuse
Make a signature once — drawn, typed, or uploaded — save it, and reuse it on every document instead of re-signing from scratch each time.
How to Add a Stamp to a PDF
Add a company seal, an APPROVED mark, or a logo to a PDF. How stamps differ from signatures and watermarks, and when each is the right tool.
How to Stop a PDF From Being Copied or Printed
Want to share a PDF but not let people print it or copy the text out? Here's how to switch off printing and copying with permission restrictions — and what that does and doesn't prevent.
How to Restrict a PDF (Block Printing, Copying & Editing)
Stop people printing, copying, or editing your PDF without locking them out of it. How PDF permission restrictions work, the six controls you can set, and where they help — and don't.
How to Remove Restrictions from a PDF
Got a PDF you can open but can't print, copy, or edit? Here's how to remove permission restrictions (and digital signatures) so you can use your own document freely.
How to Enable Printing and Copying on a Restricted PDF
Can't print or copy text from a PDF that opens normally? It's restricted, not locked. Here's how to re-enable printing and copying so you can use the document.
How PDF Encryption Works (And When It's Not Enough)
What PDF passwords actually protect, user vs owner passwords, why older PDFs are crackable, and when you need more than a password.
Digital Signature vs Electronic Signature
Electronic, digital, and e-signature get used interchangeably but they're different. Here's what each term actually means, legally and technically.
How to Redact a PDF (Hide Sensitive Information)
Permanently redact sensitive content from a PDF: manual marking, find-and-redact text search, or auto-detect for emails, phones, and SSNs. Step-by-step guide.
How-ToHow to Unlock a PDF (Remove Password Protection)
Remove password protection from a PDF you have the password for. Step-by-step guide, plus what to do if you've forgotten the password.
How-ToHow to Password-Protect a PDF
Add a password to a PDF so only people with the password can open it. Step-by-step guide, plus how to pick a strong password and what to do if you forget it.
How to Sign a PDF Online
Add a signature to a PDF online: draw it, type it, or upload an image. Step-by-step guide, plus how to lock the signature so it can't be moved.