Frequently Asked Questions

Common questions about Philter Desktop. For full detail, follow the links into the rest of the documentation.

How do I get Philter Desktop?

The official, signed build is provided to subscribers from philterd.ai. Because the software is open source under the Apache License 2.0, you can also read the source code and build it yourself. See Licensing & Support for how the free open-source software and the paid official product fit together.

What do I get, and what happens after I purchase?

Subscribers receive the same official signed build as everyone else; there are no separate downloads or license keys. The subscription covers the official, code-signed, maintained build, support from the team that makes it, and maintained releases. Keep your receipt as proof of purchase. See Licensing & Support.

Do my documents leave my computer?

No. All detection and redaction happen locally on your Windows machine, and Philter Desktop works fully offline. Nothing about your documents is uploaded or sent over the internet.

Can you see my documents?

No. Your files stay on your own device throughout detection and redaction, so Philterd cannot access their contents.

Is it open source?

Philter Desktop is released under the Apache License 2.0, so you can audit the source code and build it yourself at no cost. The subscription is for the official signed build, support, and maintained releases. See Licensing & Support.

What file types does it redact?

PDF (.pdf), Microsoft Word (.docx), plain text (.txt), rich text (.rtf), spreadsheets (.xlsx and .csv), and email (.eml and .msg). Each type has its own page under Redacting Documents.

Can it redact scanned PDFs?

Scanned PDFs are read with on-device OCR that runs entirely on your computer, so the text in them can be detected and redacted. OCR is best-effort: its accuracy depends on scan quality, and it does not read handwriting, so reviewing the result matters even more here. See PDF.

Can I control what gets redacted?

Philter Desktop uses a configurable policy engine: you choose which kinds of information to detect, add your own terms and custom identifiers, and decide how matches are replaced with filter strategies. See Redaction Policies.

Does it remove hidden data and metadata?

For Word documents, Philter Desktop can also clean up metadata (author, company, title, and so on), comments, tracked changes, and hidden text, and for email it can strip identifying headers. These cleanups are on by default and can be turned off in Settings. See Microsoft Word and Email.

How do I know the redaction worked?

You can preview the result before saving, have Philter Desktop re-scan the finished file to check for anything still detectable, generate a redaction report, and view a before-and-after comparison. These tools reduce the chance of something slipping through, but automated detection is probabilistic, so always give an important document a human review as well. See Checking the result for anything missed.

Is the redaction permanent?

What Philter Desktop redacts is genuinely removed, not merely hidden from view: a redacted PDF is flattened to an image, so no recoverable text layer remains, and in other formats the content is replaced rather than just covered over. (This concerns what was redacted; whether everything sensitive was caught is a separate question, so still review the result.) Your original file is never changed: the result is always written to a new copy. See PDF.

Can I automate redaction?

You can use watched folders, the command line, or the Windows Explorer right-click menu for batch or individual processing.

Is my data stored securely on my computer?

Philter Desktop's local data is encrypted at rest and tied to your Windows account on that machine, with optional passphrase protection for stronger control. See Settings → Security.

What are the system requirements?

Windows 10 (version 2004, build 19041) or later, or Windows 11, 64-bit. See Getting Started.