How to Redact a PDF Properly (Why Covering Text Isn't Enough)

Redaction has one job: make sensitive content genuinely unrecoverable. A lot of tools — and a lot of people manually “redacting” documents — get this badly wrong by simply drawing a black box over text and calling it done. That doesn’t actually remove anything. Here’s why, and what a correct approach looks like.

The mistake: drawing over text

If you take a PDF and draw a black rectangle on top of a sentence using most editing tools, the original text is still there underneath the shape — it’s just visually hidden. Anyone can select the text and copy it, or run a script that extracts all text from the PDF, and the “redacted” content comes right out. This has caused real, embarrassing, and sometimes legally serious leaks — government agencies, law firms, and news organizations have all published PDFs where the redacted text was trivially recoverable.

What real redaction requires

To make content truly unrecoverable, the underlying text and data have to be gone, not just covered. The Redact PDF tool does this correctly:

1. Every page is rendered to a raster image first — text becomes pixels, not selectable data.
2. You draw black boxes directly onto those rendered images, over anything sensitive.
3. Each box is baked permanently into that page’s image.
4. The entire output PDF is rebuilt from these flattened images — one image per page — with no original text objects anywhere in the file.

Because the original vector text never makes it into the output at all, there’s nothing left to extract. Copy-paste returns nothing. Text-extraction scripts return nothing. The redacted content is gone, not hidden.

The honest tradeoff

This approach means the entire output document becomes an image — not just the redacted areas. You lose selectable and searchable text across the whole PDF, even on pages with no redactions. That’s a real cost, but it’s the correct cost for a guarantee that actually holds up. A redaction tool that preserves selectable text everywhere except the boxes you drew is, almost by definition, not doing real redaction.

When to use this

Reach for proper redaction whenever a document will be shared outside a trusted circle and contains anything sensitive — names, account numbers, medical details, case information, internal notes. If you just want to mark up or annotate a document you’re keeping internal, the regular Edit PDF tool is faster and keeps text selectable, because there’s nothing sensitive at stake.

A note on privacy

Rendering, redacting, and rebuilding the PDF all happen locally in your browser — the document you’re redacting is never uploaded anywhere, which matters given what you’re likely redacting it for.