Redact PDF

Black out names, numbers, and other sensitive information in a PDF — free and entirely in your browser. Redacted pages are flattened to images so the hidden content is truly removed, not just covered.

How to redact a PDF

1. Add your PDF. Drag and drop the document onto LambiPdf, or click “Choose files.”
2. Open the Redact tool and drag a black box over each piece of sensitive text or imagery.
3. Apply & save. On save, redacted pages are rasterized (flattened to an image), so the covered text can't be copied or recovered.

Real redaction, done privately

Simply drawing a black rectangle in some editors still leaves the original text underneath, where it can be copied or extracted. LambiPdf flattens each redacted page to an image so the underlying content is genuinely gone. And because it all happens in your browser, the confidential document is never uploaded to a server.

Worked example: remove a fictional account reference

Download the fictional membership note. Before redaction, its selectable text includes DEMO-4821-7390. This is a made-up reference, and the name and email are fictional too.

1. Open Redact and add the sample. Draw a box over the complete account-reference line, including any label or nearby characters you want removed.
2. Leave Apply to all pages off for this one-page edit. Inspect the box at a readable page size and preview the result.
3. Save and download the reviewed PDF. Reopen that downloaded file. Confirm that the line is blacked out and the other information you intended to keep is still visible.

The result generated for this example was checked by extracting its text: the reference was absent. The edited page is flattened to an image, so its remaining visible text is no longer selectable either. Visual inspection and a text check complement each other; neither should be skipped for sensitive material.

Black boxes, signatures and watermarks have different jobs

A signature image or ordinary black annotation can cover words without removing the underlying text. The Redact tool flattens marked pages when generating the result. Use the actual Redact operation rather than a stamp, watermark or a rectangle in another application.

A practical pre-sharing checklist

• Open the downloaded output, not just the editor preview or the original file.
• Check every intended page at a readable zoom, including page edges and repeated references elsewhere.
• Try searching or copying the redacted reference. On this flattened example, the page has no selectable text.
• Review other pages, metadata, attachments and information still visible in images. A box in one place is not a search-and-remove command for the entire document.
• Keep the unredacted original in an appropriate location and share only the checked output.

This demonstration verifies a specific sample and is not a certification for every PDF structure or confidentiality requirement. Device security, extensions, backups and your organization's rules still matter.

More free PDF tools

Redact PDF — FAQ