How to black out numbers on a PDF before you send it

To redact a PDF properly, the numbers have to be gone from the file, not just hidden under a black shape someone can move or copy text from. ScanMojo's Safe Copy does that on your iPhone or Android phone: it blacks out what you choose and redraws each page as a picture, so nothing under a box is left in the PDF. Making and previewing a Safe Copy is free; sharing it is part of ScanMojo Pro, and your own scan stays as it is.

This is a ScanMojo Pro tool: $39.99 a year with a 7-day free trial, or $6.99 a month (U.S. prices). Scanning and PDF export stay free.

  1. 1

    Scan the page, or bring in the PDF

    Scan the statement, bill or letter. For a PDF you already have, like a downloaded bank statement, open Tools › Import a file and pick it.

  2. 2

    Open Safe Copy

    Open the document and tap Share › Safe Copy. The pages open in an editor; the document itself doesn't change.

  3. 3

    Tap Cover Numbers

    ScanMojo reads the page on your phone and puts a black box over lines with long numbers, like account, card and policy numbers. It covers the whole line, so look at what it boxed.

  4. 4

    Check each page and add your own boxes

    Drag across anything else to black it out, such as transactions, a date of birth or an address you don't need to show. Tap a box to remove it. Swipe through every page.

  5. 5

    Mark it and share it

    Optionally type what the copy is for, or pick one of the suggested watermarks, and leave "Add today's date" on to stamp the date. Then tap Share Safe Copy.

Why a black box isn't always enough

Drawing a rectangle over a PDF in a markup tool usually puts a shape on top and leaves the text underneath. Whoever gets the file can often select it, search it or paste it somewhere else.

A Safe Copy is made differently. Each page is drawn again as an image with the boxes painted in, and no text layer goes with it, so nothing under a box can be copied or searched. The trade-off is that the copy itself isn't searchable, which is usually what you want for something you're handing over.

What to black out on a bank statement or bill

Ask, or read the request again, for what they actually need. A landlord checking income usually wants your name, the bank's name, the dates and the deposits, not every purchase or the full account number. An insurer may need the claim or policy number, so don't cover a number they've asked for.

Cover Numbers catches long runs of digits, including ones printed with spaces or dashes. It won't find a name, an address or a short number, so check each page yourself before you share.

What's free

Scanning, importing, Cover Numbers and the preview are free, with no ads. Sharing the Safe Copy is part of ScanMojo Pro. Nothing is uploaded to be redacted: your scans stay on your phone unless you share them or turn on sync to your own iCloud Drive or Google Drive.

Questions

Can I redact a PDF on my iPhone or Android phone?

Yes. In ScanMojo, open the document, tap Share › Safe Copy, tap Cover Numbers or drag over what you want hidden, and share the copy. It works on scans and on PDFs you import.

Is the text under the black boxes really gone?

Yes. A Safe Copy redraws every page as a picture with the boxes painted in and leaves out the text layer, so the hidden parts can't be copied, searched or lifted out of the file.

Does it find every number on its own?

No. Cover Numbers boxes lines with long numbers, and then you check each page and drag across anything else. You decide what's covered.

Is redacting free in ScanMojo?

Making a Safe Copy and previewing it is free. Sharing it is part of ScanMojo Pro. Scanning and sharing a regular PDF stay free, with no ads and no watermark.

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