How to use it
Drop a picture on the page, paste one with ⌘V or Ctrl+V, or press Choose a file.
Drag over the part you want pixelated. You can add up to 30 boxes. To pixelate the whole picture, press Whole picture.
Slide Block size until you can't tell what was there. Bigger blocks hide more.
Press Download PNG, or Copy to paste it straight into a message.
Look at the picture under the buttons. It's the file you just made, read back from the file itself. If a face still comes through, make the blocks bigger and download again.
Doing it well
Go bigger than you think. If you can still guess a letter, or whose face it is, the blocks are too small.
The block size is a share of the picture's shorter edge, not a fixed number of pixels, so the same screen captured at two sizes gets the same look.
Pixelating hides less than it looks like. Someone with the right tools can sometimes work out what was under it. So use it for a face in the background or a screen you only want softened. For passwords, keys, account numbers, names and email addresses, use Redact, which is a solid block with nothing under it.
Pixelate and Redact, side by side
VizShot has Pixelate (B) in its editor, with Redact (E) beside it, and the editor's own hint says it plainly: "Pixelate is reversible. Use Redact for anything private." Redact or pixelate? explains when to use which, and you can download VizShot and try it free for 14 days.
Questions
Can pixelation be undone?
Sometimes. Big blocks make it harder, but someone with the right tools can occasionally work out what was under a pixelated area. If it's private, don't pixelate it. Cover it with a solid block instead, or read how to redact a screenshot for the options.
Is my picture uploaded?
No. The picture is opened, pixelated and saved inside your browser, and no request carries it anywhere. Your browser's network panel will show you if you want to check.
Is pixelating the same as blurring?
No. Blurring smooths an area, and pixelating swaps it for coarse squares. Either can sometimes be undone, so neither is for a secret. VizShot keeps Pixelate for softening a face or a background and Redact for anything private, and it doesn't blur, on purpose. The blur a screenshot page has the app version in three steps.
How big should the blocks be?
Big enough that you can't tell what was there. If a letter or a face still comes through, go up a step.
Will it pixelate the whole picture?
Only the boxes you draw. To pixelate everything, press Whole picture, which puts one box over the whole thing.
What file do I get?
A PNG with the same width and height as the picture you dropped in. Anything from the original file's metadata, such as the camera or the location, isn't carried over. The picture under the buttons is that file, read back.