Offline PDF & OCR Bulk Sanitization
Redact Scanned Documents Locally in Your Browser
AI Summary / Key Takeaways
"Protect sensitive scanned files without uploading them to cloud APIs. We compile Tesseract OCR and PDF rendering engines into WebAssembly (WASM), allowing your browser to parse, scan, and redact images and PDFs completely offline. Available exclusively in the Site Workspace."
Need to scrub non-searchable PDFs?
Unlock Local OCR for scanned documents in PRO.
Interactive PII Detection & Sanitization Sandbox
Test real-time client-side RAM tokenization. Choose a specialized preset or paste your own raw prompt to test instant reversible redaction.
The Challenge with AI Data Workflows
Uploading scanned contracts, medical records, or tax forms to cloud-based PDF redactors exposes raw PHI and PII to third-party sub-processors. This breaks compliance under HIPAA and CCPA, requiring complex legal agreements just to redact a file.
How It Works
Import Document
Drag and drop any PDF, DOCX, PNG, or JPG document. The file is held locally in browser RAM as a private Blob object with zero cloud upload.
Local WASM Extraction & OCR
Native PDF text layers are parsed via PDF.js. Scanned or flattened documents trigger local WebAssembly OCR (Tesseract.js v5) in a background Web Worker.
Client-Side Tokenization & Masking
Detected PII (names, emails, SSNs, financial IDs) is replaced with deterministic RAM tokens. Export sanitized text or copy directly into LLM prompts.
What Teams Achieve with Local PII Masking
Swipe to read verified reviews
Supported Formats & Limitations
Supported Formats
System Limitations
- High client-side RAM requirement for Tesseract.js WASM (~500MB+ for large PDFs)
- Optimal OCR accuracy requires > 200 DPI resolution
- Heavily skewed or handwritten text may experience reduced NER detection accuracy
Local PDF & OCR Sanitization Architecture
Modern corporate workflows rely heavily on PDFs, scanned agreements, and screenshots. However, submitting scanned documents to generative AI tools like ChatGPT, Claude, or Copilot exposes sensitive data when cloud platforms run backend Optical Character Recognition (OCR). PrivacyScrubber solves this by executing zero-trust client-side sanitization directly inside browser memory before text reaches third-party AI models. Learn more on our features hub.
Dual Output Modes: Contextual AI Tokens vs. Court-Grade Blackout
Depending on your downstream operational pipeline, PrivacyScrubber allows 1-click toggling between two specialized redaction formats:
Replaces names, emails, and account numbers with structured tokens ([NAME_1], [EMAIL_1]). Preserves syntactic relationships for ChatGPT, Claude, and Copilot while enabling 1-click reversible restoration in RAM.
Renders permanent, solid black raster bars over pixel coordinates. Completely purges the underlying vector text layer and OCR streams to prevent copy-paste leaks via Cmd+A or pdftotext.
Dual-Pipeline Processing Architecture
PDF Flattening for Deep Redaction
Complex enterprise PDFs often contain hidden text layers, obfuscated metadata, or layered image masks designed to bypass simple text extraction. Enable the pdfFlattenToggle before importing to force the browser to rasterize the document into a single flat image layer, guaranteeing that our local WASM OCR engine analyzes exactly what a human sees on the page.
PrivacyScrubber dynamically inspects incoming documents and selects the optimal local processing pipeline:
Pipeline 1: Digital Text PDFs
Leverages PDF.js to parse embedded vector font structures in native PDFs (invoices, exported DOCX files). Instantaneous extraction without optical rendering.
Pipeline 2: Scanned Images & OCR
Passes raster bitmaps (PNG, JPG, scanned PDF pages) to Tesseract.js v5 (WASM) running in isolated Web Worker threads with zero-copy OffscreenCanvas memory transfer.
Comparative Analysis: Local WASM OCR vs. Cloud OCR APIs
Enterprise InfoSec teams increasingly prohibit cloud OCR sub-processing due to third-party vendor risks. The table below illustrates the structural advantages of PrivacyScrubber's client-side engine:
| Evaluation Vector | Cloud OCR APIs (AWS/Google/Azure) | PrivacyScrubber Local WASM OCR |
|---|---|---|
| Execution Location | Remote Cloud Server | 100% Local Browser RAM |
| Network Requirement | Active High-Speed Internet | Airplane Mode Verified (Offline) |
| Regulatory Sub-Processor Risk | Requires DPA / BAA & Vendor Audit | Zero Vendor Data Transfer |
| Processing Latency | 500ms – 3000ms Network Roundtrip | Sub-100ms In-Memory Extraction |
| Cost Model | Per-Page Metering ($1.50 per 1k pages) | Flat Unlimited (PRO / TEAMS) |
Industry-Specific Scanned Document Use Cases
Local OCR sanitization caters to specialized compliance requirements across enterprise sectors:
- Legal & Discovery: Redact client identities and financial figures from scanned litigation depositions and court exhibits. For legal framework details, explore our scanned deposition redaction guide.
- Healthcare & Clinical Research: Neutralize all 18 HIPAA PHI identifiers from scanned medical intake forms and lab charts. Review the HIPAA clinical note sanitization workflow.
- Accounting & Tax Advisory: Anonymize SSNs, EINs, and income schedules from flattened PDF tax returns before using LLMs for tax analysis. See the scanned tax return anonymization guide.
- HR & Talent Acquisition: Extract and sanitize candidate resumes offline to prevent demographic bias and protect personal contact info during screening. Read the HR bulk resume OCR masking guide.
- Format & Metadata Security: Avoid hidden text leaks and visual redaction flaws by purging PDF metadata and EXIF data. Consult our PDF metadata sanitization analysis.
Verify Zero-Server Operation via Airplane Mode
You can audit PrivacyScrubber's offline OCR engine yourself: load the Secure Workspace, disconnect your internet connection (or enable Airplane Mode), and process any scanned PDF or image. The WASM OCR engine will extract and redact PII without making a single HTTP network call.
Explore Batch Folder ScrubbingEnterprise Impact Metrics
By running OCR via Tesseract.js locally, enterprises achieve 0 bytes of data exfiltration risk and eliminate the $0.05/page API costs typically associated with cloud vision providers.
Client-Side Reliability & Audit Verification
Powered by the Zero-Trust Sanitization Engine (ZTDS). All detection, tokenization, and regex evaluation execute 100% inside your local client process boundary — eliminating cloud proxies, intermediate servers, and third-party data retention risks.
Step-by-Step Guide
How to use this feature
Select File
Click Upload or drag a scanned PDF or image into the PrivacyScrubber workspace.
Local WASM Processing
The local engine automatically selects native PDF parsing or WebAssembly OCR based on document structure.
Review Token Map
Color-coded tags highlight protected PII entities directly on screen before prompt export.
Export Sanitized Text
Copy clean text or download the sanitized file. Verify with Airplane Mode — zero network requests are made.
Frequently Asked Questions
How does PrivacyScrubber process scanned PDFs without a backend server?
PrivacyScrubber compiles C++ OCR libraries into WebAssembly (WASM). When a scanned PDF or image is dropped into the workspace, a dedicated Web Worker thread executes Tesseract.js v5 and PDF.js directly on your computer's CPU, keeping all file data inside volatile browser RAM.
What is the difference between visual redaction and true OCR text sanitization?
Visual redaction tools simply draw black rectangles on top of PDF layers, leaving underlying OCR text, EXIF metadata, and edit histories exposed. PrivacyScrubber executes true Secure Raster Flattening: it parses the document in local RAM, permanently overwrites PII coordinates at the pixel level, and creates a brand-new PDF without any hidden text streams or underlying OCR layers, making copy-paste extraction physically impossible.
What scan resolution (DPI) is recommended for maximum OCR accuracy?
Tesseract.js v5 achieves 97–99% character accuracy on printed Latin documents scanned at 300+ DPI. Documents scanned at 200–300 DPI achieve 94–97% accuracy. For low-resolution scans (under 150 DPI), run local preprocessing or review detected tags manually.
Can PrivacyScrubber process multi-page PDFs or batch document folders?
Yes. PRO and TEAMS tiers support multi-page PDFs and batch folder processing up to 50 files simultaneously. Web Workers process pages in parallel threads without freezing your browser interface.
Does the OCR engine require an active internet connection?
No. Tesseract.js language assets (~8 MB) are cached locally in IndexedDB on first run. Subsequent PDF and OCR operations execute 100% offline, verifiable via Airplane Mode.
Which international languages are supported by local OCR?
The core language pack includes English, Spanish, French, German, Italian, and Portuguese. Additional language datasets can be initialized on demand for specialized international compliance workflows.
Is PDF OCR processing compliant with HIPAA Safe Harbor and GDPR Article 32?
Yes. Because zero PII leaves your machine, no sub-processor data processing agreement (DPA) or Business Associate Agreement (BAA) is required for third-party cloud OCR APIs. Data never enters external networks.
Protect Your Team's AI Prompts in Under 30 Seconds
No server uploads. No account required. 100% offline in your browser's local RAM.
