Securely Mask Sensitive PDF Data
Hide sensitive information from your PDF locally.
Simple, private, and entirely in your browser.
Drop your PDF here
or
Your file stays on your device · No upload
Choose a PDF from your device
Draw over sensitive info
Download your masked PDF
Why redact your PDFs locally without a server?
Learn why in-browser local redaction minimizes data exposure for your sensitive files before sharing.
Zero Server Uploads
Document content is processed entirely inside your web browser and is never sent to our servers for redaction. Technical assets needed for rendering are cached in your browser.
Tamper-Proof Flattening
Black boxes permanently replace pixels and destroy the underlying text layer. It is technically impossible to select, copy, or extract the redacted text.
GDPR & Compliance Ready
Designed to prevent inadvertent data leakage and comply with privacy best practices. You maintain full ownership and control of your source and output files.
Beware of fake masking with simple black highlights!
Many people try redacting documents in ordinary PDF viewers by drawing black boxes or highlighter shapes over text. In a standard PDF reader, this underlying text remains selectable, searchable, and easily extracted with a simple copy-paste.
✓ Our tool eliminates this vulnerability with HD image rasterization (tamper-proof flattening). The original text under masked zones is permanently destroyed.
Which documents should you redact before sharing?
Mask Social Security Numbers, tax identifiers, and sensitive banking lines on payslips and tax returns.
Mask full account numbers or branch addresses when only sharing secondary proof of funds.
Redact the machine-readable MRZ band, national identification numbers, or signatures to prevent identity theft.
Mask confidential pricing clauses, subcontractor rates, or employee personal data.
Frequently Asked Questions (FAQ)
Are my PDF files uploaded to the internet?
No. The contents of your PDFs are never uploaded to any remote server. Rendering and redaction are performed locally inside your browser via WebAssembly and HTML5 Canvas.
How do I know the black boxes are truly permanent?
When the default HD Tamper-Proof Flattening is enabled, masked pages are re-rasterized into high-resolution graphic layers. The underlying text characters and vector glyphs are permanently destroyed.
Is this tool free and without registration?
Yes, PDF Masker is 100% free, unlimited, and requires no account creation or subscription.