How to Redact a PDF Online for Free — Step-by-Step

Why redaction is different from just covering text with black

Before we get into the how, understand the trap. When people ask “how do I redact a PDF,” most free online tools answer with a drawing feature — a black rectangle you place over the text as a PDF annotation. The text still exists in the file underneath. Anyone who opens the redacted PDF in Adobe Reader can:

• Select the text under the black rectangle and copy it out.
• Right-click the rectangle and choose “Delete” to reveal the original.
• Extract the raw text with any PDF library (pdf.js, PyPDF2, pdftotext) and read everything.

This is exactly how court filings, government FOIA responses, and corporate settlement agreements have leaked personal information for years — the Manafort filing, DOJ Michael Flynn documents, and dozens of high-profile matters where lawyers used a covering-shape and thought they had redacted the file.

Real redaction permanently removes the text from the PDF. After you download, the redacted words cannot be selected, cannot be copied, cannot be extracted with any software, cannot be revealed by removing an annotation — because there is no text there anymore. The pixels where the text used to be are just black.

Step 1: Open the free redact tool

Go to scanpdfonline.com/pdf-redact in any modern browser: Chrome, Edge, Firefox, Safari, or the built-in browser on iPhone / Android. No account. No install. No Adobe Acrobat subscription. No trial-with-credit-card. It loads and it works.

If your PDF has personal information in it — an SSN, a credit-card number, medical records, a passport copy — you may be wondering whether uploading it to yet another random tool is safe. Our tool never uploads. Everything happens inside your browser using the pdf.js and pdf-lib libraries. You can verify: open your browser's Developer Tools (F12), switch to the Network tab, then drop your PDF. You'll see the page load its own scripts but zero outgoing requests carrying your file.

Step 2: Drop your PDF onto the box

Drag the PDF from your file manager onto the drop zone, or tap the box and pick from a picker. On iPhone, that means the Files app, iCloud Drive, or an email attachment. On Android, that means Files, Google Drive, or your local storage. On a Mac / Windows / Linux desktop, drag straight from Finder or Explorer.

The tool renders every page of your PDF and starts scanning for personal information. On a typical 5-page PDF this takes about 2 seconds.

Step 3: Review the auto-detected suggestions

The auto-scan looks for six kinds of personal information in the PDF's text layer:

• Social Security Numbers in the standard US format XXX-XX-XXXX.
• Credit-card numbers — 13-19 digits with optional spaces or dashes, validated against the Luhn checksum so a phone number or invoice reference isn't mistaken for a card.
• Phone numbers — US-style with parentheses or dashes, international with a “+” country code.
• Email addresses in the standard user@domain.tld form.
• IBAN — European bank account numbers.
• Dates of birth — three common numeric forms.

Each match appears as a colored box with a dashed border, meaning “suggested but not yet applied.” This is intentional — redaction is destructive, so the tool never redacts anything automatically. You have to actively opt each detection in.

Step 4: Choose what to redact

You have three ways to enable a redaction:

1. Click a single box on the page thumbnail — the border turns solid, meaning it will be blacked out on export.
2. Use a category pill — the summary bar has pills like “SSN 1” and “Card 1.” Click a pill to enable every detection of that kind at once.
3. Draw a manual box — click “Draw a Manual Box,” then drag a rectangle over any region on any page. Useful for names, home addresses, dates, license plates, medical record numbers — anything the auto-detect doesn't catch.

If you accidentally include something, click the box again to toggle it off, or double-click to remove it. Undo (Ctrl+Z / Cmd+Z) and Redo (Ctrl+Y) work as expected. The Delete key removes the currently selected box.

Step 5: Redact & download

When your selections look right — the counter at the top will say something like “3 of 5 marked” — click Redact & Download. What happens under the hood:

1. Each page is rendered to a bitmap canvas at 1.5× scale.
2. Solid-black rectangles are painted onto the bitmap at the marked coordinates.
3. Each bitmap is encoded as a JPEG.
4. The JPEGs are packaged into a fresh PDF using pdf-lib.
5. Your browser downloads that fresh PDF.

The original text objects for the redacted regions no longer exist in the output PDF. There is nothing to select, nothing to copy, nothing to extract. Open the file in Adobe Reader, select the black area, and paste into a text editor: you get an empty clipboard.

How to redact a PDF on iPhone (step-by-step)

1. Open scanpdfonline.com/pdf-redact in Safari on your iPhone.
2. Tap the drop zone.
3. Choose Files, browse to the PDF (in iCloud Drive, On My iPhone, or a linked service like Google Drive / Dropbox), tap the PDF.
4. Tap each colored box you want redacted, or tap a category pill (SSN, Card, etc.) at the top.
5. Tap Draw a Manual Box and drag over any additional area — names, home addresses — with your finger.
6. Tap Redact & Download. The redacted PDF downloads to your device.
7. Share via Mail, Messages, WhatsApp, or save back to Files.

Works identically on iPad. On iPadOS you can also drag the PDF from Files into the Safari window as a split-screen gesture.

How to redact a PDF on Android (step-by-step)

1. Open scanpdfonline.com/pdf-redact in Chrome on your Android phone.
2. Tap the drop zone.
3. Choose the PDF from Files, Google Drive, Dropbox, or wherever it's stored.
4. Tap the boxes / category pills to enable redactions.
5. Use Draw a Manual Box for anything the auto-detect missed.
6. Tap Redact & Download.

Works on Samsung Galaxy, Google Pixel, Xiaomi, OnePlus, OPPO, Motorola — any Android device with a modern Chrome or Chromium-based browser.

How to redact a PDF on Mac / Windows / Linux

Same steps as above, in Chrome, Edge, Firefox, or Safari. On desktop you can multi-select PDFs from your file manager and drag them in, but the tool works on one PDF at a time — if you need to redact several documents, do them one by one. To batch-process a folder's worth of files, you'd need a paid enterprise tool; for one-off documents, this is the fastest and safest way.

Common mistakes to avoid

Do not use a PDF viewer's “highlight” or “draw shape” feature to hide text

The same warning as before: Preview on macOS, Adobe Reader, Foxit — all let you draw a filled rectangle over text as an annotation, but the text underneath stays extractable. If the document will ever leave your device, a covering annotation is not redaction; it's security theater.

Do not screenshot a PDF and share the screenshot as redaction

You'd think a screenshot is safe because it's an image. But if you screenshotted before covering the sensitive text, or if you cropped a screenshot that has the sensitive text just off-screen (some phone screenshot tools save the full page), the original data still exists. Also, screenshots are typically much larger than a redacted PDF because they store the whole page as a rasterized image at screen resolution.

Do not skip the “flatten” step in Acrobat Pro

If you do use Acrobat Pro's redact tool, you must apply the redactions (which flattens them into the page). If you save and share a PDF with pending unapplied redactions, the recipient sees the black rectangles as removable annotations. Our tool doesn't have this footgun — every export is already flattened.

Do not forget to review page thumbnails one more time

Before clicking Redact & Download, scroll through every page. Auto-detect might have missed a personal detail (a name in the header, a signature, a case number written by hand). Draw a manual box for anything the regex didn't catch.

How our redaction compares to Adobe Acrobat, iLovePDF and Smallpdf

When you need to redact a PDF the safe way

• Court filings — plaintiff addresses, minor children's names, medical details.
• Insurance claims — hiding medical record numbers or SSN before mailing.
• Background checks — HR shares employee records with a third-party screener, needs to redact SSN and DOB.
• Loan / mortgage applications — accountant needs to see income but not full account numbers.
• Government / FOIA responses — agency shares a document with the public, must redact source-protecting details.
• Journalism — verifiable leak of a document while protecting source identity.
• Personal ID copies — send a passport copy for verification but redact the number.
• Selling on eBay / Craigslist / Facebook Marketplace — proving a receipt without exposing your address and card number.

What if the redacted PDF looks blurry?

Our tool renders each page at 1.5× the PDF's native resolution before rasterizing, then encodes the result as high-quality JPEG (quality 0.9). For 99% of documents this is indistinguishable from the original at normal viewing zoom. If you notice softness on a very detailed technical drawing or a small-print legal document zoomed to 200%+, that's a fair tradeoff for the guarantee that the redacted text is truly gone.

Ready?

→ Open the redact tool and try it with your PDF. It works in-browser, downloads a redacted copy in seconds, and nothing ever gets uploaded.