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Forme performs true PDF redaction: text is removed from the content stream, not just hidden behind a black box. This is the difference between compliance-grade redaction and a cosmetic overlay that can be trivially reversed.

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Why Black Boxes Aren’t Enough

A black rectangle drawn over text in a PDF does not remove the text — it only hides it visually. The text remains in the PDF content stream and can be extracted by:
  • Copying and pasting from the PDF
  • Using PDF text extraction tools
  • Inspecting the raw PDF file
This is not a theoretical risk. Improperly redacted court documents, government filings, and legal briefs have leaked sensitive information because authors used annotation-based “redaction” tools that only add a visual overlay.

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How Forme Redacts

When you call POST /v1/redact, Forme:
  1. Decompresses content streams — PDF content streams use FlateDecode compression. Forme decompresses them to access the raw page description operators.
  2. Identifies text operators — PDF draws text using operators like Tj (show text), TJ (show text with positioning), ' (move to next line and show text), and " (set spacing and show text). Forme identifies which text operators fall within redaction regions.
  3. Removes text operators — Text operators within redacted regions are removed from the content stream entirely. The text data no longer exists in the PDF.
  4. Draws visual overlay — A black (or custom-colored) rectangle is drawn where the text was, providing a clear visual indicator that content has been redacted.
  5. Recompresses content streams — The modified content stream is recompressed with FlateDecode.
  6. Scrubs metadata — Document metadata is automatically cleaned (see below).

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Metadata Scrubbing

Every redaction automatically scrubs document metadata. This is not optional — metadata often contains sensitive information that authors don’t realize is embedded. What gets removed:
  • Author name
  • Creator application
  • Edit history
  • Comments and annotations
What gets replaced:
  • /Producer → "Forme"
  • /ModDate → current timestamp

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Three Ways to Redact

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1. Coordinate Regions

Draw precise rectangles over areas to redact. Best for known, fixed layouts where content position is predictable. This is what the dashboard’s “Draw” mode uses. 
{
  "pdf": "<base64>",
  "redactions": [
    {"page": 0, "x": 100, "y": 200, "width": 150, "height": 20}
  ]
}

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2. Text Search

Find text by literal string or regular expression. Best for dynamic content where you know what to redact but not exactly where it appears. 
{
  "pdf": "<base64>",
  "patterns": [
    {"pattern": "Jane Doe", "pattern_type": "Literal"},
    {"pattern": "\\d{3}-\\d{2}-\\d{4}", "pattern_type": "Regex"}
  ]
}

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3. Presets and Templates

Use built-in presets for common sensitive data types, or save reusable sets of patterns as redaction templates. 
{
  "pdf": "<base64>",
  "presets": ["ssn", "email", "phone"],
  "template": "hipaa-patient-record"
}
Available presets:
PresetPattern
ssnUS Social Security Numbers (XXX-XX-XXXX)
emailEmail addresses
phoneUS phone numbers
date-of-birthDate patterns (MM/DD/YYYY, YYYY-MM-DD, etc.)
credit-cardCredit card numbers
All three methods can be combined in a single request.

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Verifying Redaction

After redacting a PDF:
  1. Open the redacted PDF in Chrome (not macOS Preview)
  2. Try to select text in the redacted areas
  3. If the redaction worked, there will be nothing to select — the text no longer exists
macOS Preview may show a text cursor in redacted areas. This is a rendering artifact — the text is actually removed. Always verify in Chrome or Adobe Acrobat.

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Known Limitations

  • WinAnsi encoding only: Text search and pattern matching works on standard Western-encoded text (WinAnsi/Windows-1252). CJK, Arabic, and other non-WinAnsi encoded text cannot be found by text search — use coordinate redaction instead.
  • Images and vector graphics: In v1, images and vector graphics within redacted regions are covered by the visual overlay but not removed from the content stream. True image redaction is planned for a future release.
  • Maximum 50 patterns per request: Keep the total number of patterns (including those expanded from presets and templates) under 50.

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Compliance Use Cases

  • HIPAA: Redact patient names, SSNs, dates of birth, and medical record numbers before sharing
  • GDPR: Remove personally identifiable information from documents shared with third parties
  • FOIA: Redact exempted information from public records requests
  • Legal Discovery: Protect privileged information in document productions
  • Internal Audit: Remove sensitive details before sharing reports across departments