Why black out text properly matters
Sometimes an image contains text that shouldn't be shared as-is. Whether it's a scanned form with a signature or ID number, a photographed letter with someone's home address, or a document you're using as an example that still has real, personal details in it, blurrer's Text box tool lets you black out that text completely, right in your browser, with a solid fill that fully overwrites the pixels underneath, not a translucent overlay that leaves the original recoverable.
This distinction matters more than it sounds. A well-known failure mode in document redaction is drawing a shape over sensitive text without actually destroying the underlying data. The "redacted" text can sometimes still be selected, copied, or recovered because the tool only added a visual layer on top. blurrer doesn't work that way: every edit is drawn directly into the image's pixels and flattened when you download, so there's no separate text layer left underneath to extract.
Common uses
- Redacting scanned forms, applications, or contracts before sharing them as examples
- Covering an address, ID number, or account number in a photographed document
- Blacking out a signature before posting or sending a document publicly
- Sharing financial or medical paperwork with specific fields hidden
- Preparing a sample or template document that still contains real personal data
How to black out text in an image
- Upload the photo or scan. Drop it in or click to choose a file.
- Zoom in so you can line the box up precisely with the text — switch to Move and pinch or scroll to get a closer view.
- Select the Text box tool and set the background color to solid black at 100% opacity for a standard redaction look.
- Draw a box over each line or field you need to black out, extending slightly past the edges of the text.
- Add a label if it's useful — for example, typing "REDACTED" inside the box — or leave it blank for a plain black bar.
- Download the finished image as PNG for the sharpest result on text-heavy documents.
Tips for redacting a document image cleanly
Documents are usually flat and evenly lit, which makes precise redaction easier than on a typical photo, so take advantage of that by zooming in and lining boxes up tightly against the edges of each field, rather than leaving generous margins that might spill into an adjacent line you didn't mean to cover. If a document has a field repeated in more than one place (an account number in a header and again in a footer, for instance), redact every occurrence, not just the most obvious one. And if you're preparing a document as a public example or template, double check for details that are easy to overlook because they don't look like "personal data" at a glance, like case numbers, internal reference codes, or dates that could identify a specific person's record.
Frequently asked questions
Is a black box actually secure, or can the text underneath be recovered?
It's secure by design. Once you draw a Text box and download the image, that area's pixels have been permanently overwritten and the file is flattened into a single image. There's no hidden text layer, vector shape, or transparency left behind for anyone to peel back. This is different from some document tools where a black rectangle is drawn on top of a document while the original text remains selectable underneath.
How secure are my uploads?
Your original image is encrypted in your browser. The redacted version you download never leaves your device at all, it happens entirely in your browser.
Blur vs. black box — which should I use for redacting text?
Use the solid Text box for text specifically. Blurring can leave partial letterforms visible, especially with large or bold fonts, once the image is compressed or zoomed in. A solid box removes that risk entirely by replacing the pixels with a flat color instead of just distorting them.
Can I redact handwritten notes or a signature the same way?
Yes. blurrer works on the image itself, not on recognized text, so it redacts handwriting, printed text, stamps, or signatures exactly the same way. Draw a box over it and it's covered.
Is blurring reversible?
For the Blur tool, no. The original detail is discarded, not just hidden, once the image is downloaded. For text specifically, the solid Text box goes a step further: it doesn't blur or distort the original pixels at all, it replaces them outright, which is why it's the recommended tool for redacting text.
Can I add a label like "REDACTED" instead of leaving a blank box?
Yes. After you draw a Text box, you can type an optional label that appears centered inside it, useful for making it clear to a reader that something was intentionally removed, rather than leaving them to guess.