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Mykola Melnyk
Mykola Melnyk

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I Built a Windows App That Actually Removes PII From PDFs (Not Just Covers It)

PDF Redaction Studio Desktop sign-in screen

Redacting a PDF sounds simple until you actually have to do it properly. Drawing a black rectangle over a name or an SSN doesn't remove it — the text is still sitting underneath, extractable with a copy-paste or a basic PDF parser. Doing it right means the sensitive content is gone from the file, not hidden under a layer.

I've been working on PDF Redaction Studio Desktop, a native Windows (and Linux) app that handles this end to end: AI-based PII detection, a review step so you stay in control of what gets flagged, and an export that actually strips the matched content out of the PDF.

It just landed on the Microsoft Store, so here's a walkthrough of what it does and how it's put together.

Why a desktop app instead of just a web app

A web version already existed, but a chunk of users — legal, HR, healthcare, anyone handling regulated documents — didn't want to upload files anywhere to get them redacted. The desktop app runs the detection stack (OCR, PII/NER models, face detection) locally, so documents stay on the machine by default. No Docker, no backend to stand up, no account required to just open a PDF and start reviewing it.

The dashboard

Once installed, you land on a dashboard that tracks documents, completed redactions, and page usage — useful if you're processing a batch rather than a one-off file.

Dashboard showing document list, usage stats, and quick actions

Opening a document

Drag a PDF in, or click to browse. Nothing happens with the file until you tell it to.

Start Redacting Your PDF dialog with drag-and-drop upload area

Detection runs locally

This is the part I care about most. Detection can run against a cloud API or entirely in-browser/on-device using a local model — no network round-trip for the document contents. You pick the model, tune the detection threshold (higher = fewer but more confident matches), and set how many CPU threads to throw at it.

PII detection settings panel with local model selection, detection threshold slider, and CPU thread count

Reviewing what got flagged

After detection, matches are grouped by category — names, SSNs, emails, phone numbers, driver's license numbers, addresses, credit cards, faces — and highlighted directly on the page. You can filter by category, add anything the model missed, and remove false positives before committing to anything.

Redaction review UI with PII highlighted on a document page and category filters in the sidebar

Only after you're happy with the review does export actually strip the matched content from the PDF — text, embedded objects, and image regions covering faces or signatures all get removed rather than painted over.

What's under the hood, roughly

  • OCR and layout parsing for scanned documents, not just digital-text PDFs
  • A multilingual PII/NER model bundled for local, offline detection
  • Face and signature detection for scanned forms and ID pages
  • Custom rule support for anything the built-in categories don't cover — internal codenames, account numbers, whatever your compliance checklist needs

Where it stands today

Windows and Linux builds are out now; macOS is in progress. If you're already comfortable with command-line tools there's also a Snap package for Linux, and the desktop app shares the same detection engine as the web version, so behavior is consistent across both.

The free tier covers 100 pages a month, which is enough to actually try it against your own documents before deciding whether it fits your workflow.

If you try it and hit a document type it doesn't handle well — dense forms, unusual layouts, non-Latin scripts — I'd genuinely like to hear about it. That's the kind of edge case that's easy to miss without real-world documents to test against.

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Mykola Melnyk

What are you using for pdf redaction?