How to hide personal information in a screenshot (and why blur isn't enough)
By MoaMoa · Updated
What to check before you share a screenshot, why blurring or pixelating text can be undone, and how to cover details so they're really gone from the saved image.
Screenshots show more than you think
A screenshot of a chat, a bank app or an order confirmation often contains more than the one thing you want to show: names, phone numbers, email addresses, account or order numbers, addresses, QR codes and barcodes, profile photos, and the time and battery icons that hint at where and when.
Before sharing, go through the image corner to corner. Notifications at the top, browser tabs and address bars, and the edges of a document are easy to miss.
Why blur and pixelation are not safe
Blurring or pixelating text looks like it hides it, but it doesn't always. Text has a known shape: if someone can guess the font and size, they can try candidate words or numbers, blur them the same way and compare the results. Researchers have shown this works on pixelated passwords and numbers, especially short ones like card endings or codes. A weak blur can also simply be read by squinting or sharpening.
A solid box is different. Once the area is filled with one color and the image is saved, the original pixels under it are gone. There is nothing left to reverse.
Be careful with apps that let you draw a box on a screenshot but keep the original underneath as an editable layer, such as some PDF editors and slide tools. Always share a flattened image, not the editable file.
Cover details with MoaMoa
- Open Edit a screenshot and choose a screenshot or any photo. On a computer you can also paste one with Ctrl+V or ⌘V.
- Choose Cover and drag the box over each detail. Resize it so it covers the whole line, with a little margin.
- Add an arrow, a box, numbered markers or text if you're explaining something, or crop away parts that aren't needed at all.
- Save as PNG for sharp text, or JPEG for a smaller file.
The saved image is flattened: covers are part of the pixels, and the edit history isn't stored in the file. The tool also offers Blur for decoration, and labels it as something that can sometimes be undone, with a one-click switch to a cover.
Before you send
- Open the saved file, not the editor, and zoom in on each covered area.
- Crop instead of covering when a whole section isn't needed. Less shown is less to check.
- Check reflections and small text: a name on an envelope, a screen in a mirror, a badge in a photo.
- Screenshots edited with MoaMoa are processed on your device and are not uploaded anywhere.