PDF Mask Numbers

What is PDF Number Masking?

PDF number masking is the process of automatically or manually detecting and obscuring credit card numbers, phone numbers, ID numbers, bank account numbers, and similar sensitive numeric data in PDF documents. It is critical for PCI-DSS, GDPR, and other regulatory compliance when sharing financial documents, contracts, accounting reports, and customer data.

PdfMetric's PDF Mask Numbers tool automatically detects number patterns in your document or allows manual area selection. Selected numbers are masked with a black box, asterisks, or blank space. If true redaction is applied, data is permanently removed; if overlay is used, it is visually hidden. All processing happens in your browser; documents are never uploaded to any server.

How Does Number Masking Work?

Automatic detection uses the Luhn algorithm (credit cards), regex patterns (phone: +1 XXX-XXX-XXXX, SSN: XXX-XX-XXXX), and number format rules. Credit card numbers are identified as 13-19 digit sequences passing Luhn checksum with certain BIN prefixes. Phone numbers match international format regex. ID numbers follow country rules (e.g., SSN 9 digits, TC 11 digits).

In manual masking, the user selects the area; the tool masks it. Human review after automatic detection is recommended to avoid false positives. True redaction is permanent; overlay only visually covers and leaves text selectable.

When Should You Use It?

• PCI-DSS compliance: Mask credit card numbers to meet storage and processing restrictions.
• Financial document sharing: Mask account and card numbers in documents sent to clients or auditors.
• GDPR: Remove or mask personal identifier numbers (national ID, passport).
• Accounting and tax: Mask tax ID and bank IBAN in sensitive sharing scenarios.
• Customer data: Mask phone numbers in call center or CRM reports.

Technical Details

Credit card: Luhn algorithm, 13-19 digits, BIN (first 6 digits) database. Phone: E.164, national format regex. SSN: 9 digits, dashes. IBAN: 2 letters + 2 digits + 14-30 alphanumeric. Masking: true redaction (data deleted) or overlay (black box drawn). Prefer true redaction when overlay is insufficient.

Advantages

• Automatic detection: Common formats like credit card, phone, ID are found automatically.
• Regulatory compliance: Helps meet PCI-DSS, GDPR requirements.
• Manual option: Select and mask specific areas manually.
• 100% privacy: Documents are processed in the browser and never uploaded.
• Financial document security: Protects sensitive numbers in invoices, contracts, reports.

Frequently Asked Questions

1. Upload PDF: Load the document to mask numbers.
2. Choose detection mode: Automatic (credit card, phone, ID, etc.) or manual area selection.
3. Mark or review areas: With auto detection, review results; with manual, select areas.
4. Apply masking: Click "Process" and download the masked PDF.

Tip: Always manually review after automatic detection. Remove false positives and manually add any missed numbers. Consider last-4-digits option for PCI-DSS.