How to redact a PDF properly, free and without uploading it
Caviardeur is a PDF redaction tool that runs entirely in your browser. The text you point at is removed from the produced file — it is not covered by a black rectangle. No document is sent to a server, here or anywhere else.
Hiding sensitive data in a PDF is not removing it
The usual way to "redact" a PDF is to draw a black box over the passage to hide, in a PDF reader or an image editor. That rectangle is a drawing added on top of the page: the words stay in the file underneath it. A copy-paste finds them, so does any text extractor, and the person you sent the document to needs no particular skill to come across them. That is how most "anonymised" documents leak.
Redacting for real means deleting. On a page carrying at least one zone to remove, Caviardeur turns the page into an image, paints the zones on that image, and replaces the original page with the result. No text layer is left to recover: not by copy-paste, not by extraction, not by reopening the file in another program.
What the tool actually does
- Automatic detection. Social insurance and social security numbers, IBANs, card numbers, dates, email addresses, postal codes, people's names: what is recognised is offered to you, and you decide what goes.
- Manual selection. Click a word, drag across part of a line, or draw a rectangle over an area — useful for a signature, a stamp, a photograph of a card, or any scanned document with no text layer at all.
- Highlight, strike through, underline. These marks decorate without removing anything: the text stays readable in the produced file, and the interface says so every time rather than letting a coloured line pass for a redaction.
- Verification of the produced file. Caviardeur re-reads the PDF it has just written and refuses to hand it over if a string that was meant to be gone is still extractable from it.
- Redaction report. A downloadable account of what was removed, by type and by page — without ever copying the values themselves into it.
Redact a PDF online without sending the document anywhere
Most online PDF redaction services upload your file, process it on a server and send you back the result. For a document that contains precisely what you are trying to protect — a medical record, a contract, a bank statement, a court exhibit — that means handing the original to a third party before anything has been removed from it.
Here, reading, redacting and writing all happen in your browser. Load the page, then pull the plug: the tool keeps working. Two automated tests hold that promise on every release — one checks that the application works offline, the other that no request leaves the page while a file is being processed.
Redaction and privacy law
To a regulator — GDPR in Europe, Law 25 in Quebec, PIPEDA in Canada — a document whose data is still extractable is not anonymised. A rectangle drawn on top changes nothing about what the file stores, and disclosing that document is still disclosing the data in it. The guide on redaction and privacy law sets out what you are expected to be able to show.
Frequently asked questions
Is it really free?
Yes. No account, no sign-up, no file limit, no watermark.
Can a scanned PDF, with no text, be redacted?
Yes, by drawing the zones by hand over the preview, with the mouse or from the keyboard. Automatic detection does need a text layer; the application tells you page by page when it could read nothing, rather than letting you believe there was nothing to find.
What about metadata?
Annotations, attachments, thumbnails and document metadata are stripped from the produced file. A PDF carrying an owner password — the kind that opens without asking for anything — is decrypted before any processing, otherwise the rewritten file would come out unreadable.