pdfMB

Redact PDF

Find private details, black them out and save a copy where they are really gone. Your file stays on this device.

Applying will permanently remove…

    Your original file is not changed. Keep it, because the redacted copy can’t be undone.

    • No uploadYour file stays on this device.
    • Your original stays as it isYou download a new copy. Your file is never changed.
    • Free, no sign-upNo account and no daily limit.

    What happens to your file

    Everything below happens inside your browser, on your own device. The PDF is never uploaded, so nobody else, including us, can see it or what you marked.

    1. Your browser opens the PDF with pdf.js, the PDF viewer built into Firefox, and reads the text of every page so you can search it.
    2. Each page that has a marked area is drawn as a picture, and the marked areas are painted solid black into the picture’s pixels.
    3. A brand-new PDF is built. Pages without marks are copied over exactly as they were. Pages with marks are replaced by their pictures, and nothing of the old page is copied, not even hidden leftovers.
    4. If you keep “Keep the rest of these pages searchable” on, the words outside the boxes are written back as invisible text, so the page can still be searched. Words that touch a box are left out.
    5. The new file gets no title, author or other document details, no hidden metadata and no attachments. Links and bookmarks that contain removed text are taken out.
    6. Before you download, pdfMB reads the new file and checks that the text you marked can no longer be found in it.
    In short
    1. Choose a PDF
    2. Find text or draw boxes
    3. Press “Redact and save” and confirm
    4. Download

    How to redact a PDF

    1. Choose a PDF. The first page opens large, with small page previews below it.
    2. Type a name, a word or a number and press “Find”, or tap “Emails”, “Phone numbers”, “Thai ID numbers” or “Card numbers”. Tick the results you want removed, or press “Mark all”.
    3. For anything else, such as a signature, a photo or a whole paragraph, press “Draw box” and drag across the page. Drag a box to move it, or drag a corner to resize it.
    4. Scanned pages have no text to search. Press “Find text with OCR” to read them first, then search again.
    5. Press “Redact and save”, read what will be removed, and confirm. Download the new file and keep your original somewhere safe.

    Why a black box is not enough

    Covering text with a black or white shape is not the same as removing it. In our tests, text under a drawn rectangle or under a white-out stayed in the file: the page looked clean, but the words could still be selected, copied, searched and pulled out with free tools.

    Even turning the page into a picture is not always enough. In our tests, a page that was swapped for a picture inside the same file still left the old page’s text hidden in the file, where a text-extraction tool found it.

    pdfMB avoids both problems. Marked pages are rebuilt from pixels with the black areas burned in, and the result is written into a completely new file, so the original text is not in it at all. We check this with text-extraction tools on every change to this tool.

    When people use it

    Sending documents to someone new

    Remove account numbers, ID numbers and home addresses from a bank statement, a lease or a pay slip before you email it.

    Sharing work files

    Black out client names, prices or internal emails in a contract or report before it goes outside the company.

    Copies of ID documents

    Hide the ID number, date of birth or photo on a scanned ID card when only part of it is needed.

    Thai documents

    Find Thai names and 13-digit ID numbers, including on scanned pages after reading them with OCR.

    What it can’t do

    • Redacted pages become images. Their text can’t be edited any more, and the file usually gets bigger.
    • Search only sees real text. Text inside pictures and scans is found only after “Find text with OCR”, and OCR can misread words, so check the pages yourself.
    • Quick patterns find common formats only. A number written in an unusual way may be missed, and some ordinary numbers may be picked up, so look through the results.
    • Form fields, comments and other notes on a redacted page are flattened into the picture: they look the same but can’t be edited.
    • A detail that also appears on a page you did not mark, or in a link or bookmark that pdfMB did not recognise, stays there. Search the whole file to catch every copy.
    • Password-protected PDFs, and PDFs whose owner has blocked editing, can’t be opened.

    Questions about redacting PDFs

    Is the text really gone, or just covered?

    It is really gone. Marked pages are rebuilt as pictures with the black areas painted into the pixels, and the file is written from scratch, so the old text is not inside it. pdfMB also checks the new file before you download it.

    Why do redacted pages become images?

    It is the safest way to make sure nothing survives under the boxes: text, hidden layers, form values and comments. The words outside the boxes can still be kept searchable as invisible text.

    Can I undo a redaction?

    Not in the new file. That is the point of redacting. Your original file is not changed, so keep it if you may need the full version again.

    Does it find text in scanned documents?

    Yes, after you press “Find text with OCR”. It reads the scanned pages on your device, then search and the quick patterns can find words on them too.

    Is my file uploaded?

    No. pdfMB works inside your browser, and the PDF and the words you search for never leave your device. You can check this in your browser’s network tools.

    Which details can it find automatically?

    Emails, phone numbers, 13-digit Thai ID numbers and card-like numbers. Every result is shown in a list, so you choose what to remove.