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The best PDF redaction tools compared: Acrobat, Preview, PDF24, online converters and pdfagents.ai

30 September 2026 · 9 min read

You need to send a contract, a medical letter or a bank statement to someone who shouldn't see everything in it. The tool you pick decides three things: whether the hidden text is actually gone, whether your document was uploaded to a stranger's server on the way, and how much of the afternoon it costs. Here is an honest comparison, including our own tool and where it falls short.

The only question that matters first: cover or remove?

A black rectangle drawn over text is not redaction. In a normal PDF the text is still underneath; anyone can select it, copy it, or run the file through a text extractor and read every word. This has embarrassed courts, governments and law firms repeatedly. A real redaction tool removes the underlying text and image data, or flattens the page to a picture so there is nothing left to extract. Here is how to check a redacted PDF yourself before you send it.

With that lens, the tools sort themselves into three groups.

The comparison

Tool by tool

Adobe Acrobat Pro: the reference, at a price

Acrobat's redaction is the one lawyers are trained on: mark areas or search for words and patterns, then Apply permanently removes the content and can also scrub metadata and hidden layers. Its OCR means scanned documents work too. The drawbacks are the subscription and the weight of the app; if you redact daily and someone else pays for the licence, it is the safe choice.

macOS Preview: free and correct, but entirely manual

Since macOS Big Sur, Preview has a real Redact tool (Tools → Redact) that removes the underlying content when you save. It is excellent for a page or two. It does nothing to help you find what to remove, so a twelve-page statement with a name on every page means twelve pages of hunting, and a missed occurrence is easy.

PDF24: the free Windows workhorse

PDF24 Creator is a free desktop suite whose redaction tool flattens pages so the text is genuinely gone. Manual boxes only, like Preview, but it runs locally and handles large files well. Windows users who don't want Acrobat should start here.

Online converters: convenient, but you are uploading the document

The many "redact PDF online" sites are fast and often have search. The catch is in the name: online. Your contract, medical letter or bank statement is transmitted to and processed on their servers. Most delete files after a period and say so in their policy; whether that is acceptable depends on what is in the document and who you are answerable to. For anything covered by client confidentiality, GDPR or a non-disclosure agreement, it is usually the wrong trade. Read the privacy policy, and prefer tools that state a deletion time in hours.

The "draw a box" trap

Any tool that lets you draw a filled rectangle will make a page look redacted: annotation tools in PDF readers, free editors' shape tools, exporting from Word or PowerPoint after covering text. None of them remove the text. If the tool has no feature explicitly named "redact", assume it is only covering.

pdfagents.ai Redactor: where it's better, and where it isn't yet

Our Redactor was built to fix the two complaints above: manual hunting, and uploading. When you drop a PDF and ask it to remove personal data, it first reads the whole document and proposes what it found: names and companies, email addresses, phone numbers, IBANs, card numbers, street addresses and dates of birth, with counts. You say "yes", or "only the names", or give your own list, choose a label or a plain black box, and download. That is the extra benefit: the finding is done for you, across every page, in one pass.

It runs entirely in your browser. There is no upload: the PDF, the words you mask and the result never leave your computer, which is why it is safe for documents you are not allowed to share with a converter site. Every page of the result is flattened to an image, so the hidden text cannot be recovered by selecting, copying or extracting.

Where it is behind the paid tools, honestly:

• Scans take two steps. A scanned document has no text to find, so you first say “make it searchable” (text recognition runs in your browser, in English or German) and then redact the result. Acrobat does both in one go, and its OCR copes better with poor scans.
• The output is image-only. Flattening is what makes the removal certain, but it also means the masked file is no longer searchable and is larger than the original. Acrobat keeps the surrounding text live.
• Name detection is a proposal, not a guarantee. It finds capitalised names well and occasionally suggests a heading; that is why it asks before masking. You still read the list.
• Limits: 60 pages per file, 50 terms; text recognition handles 30 pages per run.

Which should you use?

• One or two pages, a Mac: Preview.
• A confidential document with names, numbers or addresses spread through it: pdfagents.ai Redactor, then check the download.
• Poor-quality scans, or redaction every day with a budget: Acrobat Pro.
• Windows, free, manual: PDF24.
• Online converters: only for documents you would be comfortable emailing to a stranger.

Whichever you choose, run the two-minute check on the result. It is the step that separates "looks redacted" from "is redacted".