How to Pixelate Part of an Image (Faces, Plates, Private Info)

2026-06-09

Short answer: To pixelate part of an image — a face, a license plate, an address on a screenshot — open ToolKoala's pixelate tool, drop the image in, drag a box over the sensitive region, crank the block size up, and download. It runs entirely in your browser, so the uncensored version never touches a server. Which, if you think about it for two seconds, is the whole point.

The steps

Open ToolKoala's pixelate tool and drop in your image. Nothing uploads — it loads straight into your browser tab.
Select the region you want censored, or pixelate the whole image if that's the job.
Set the block size. Bigger blocks = more destroyed information. Don't be shy here (more on this below).
Check the result. Can you still guess the digits? Then go bigger.
Download. The original stayed on your device the entire time.

If it's specifically faces you're hiding, the face blur tool auto-detects them — handy for crowd shots where dragging twelve boxes by hand gets old fast.

Block size matters more than you think

Here's the uncomfortable part: a fine mosaic over text — account numbers, plates, addresses — can sometimes be reversed. The attack is simple: render every possible character through the same pixelation and compare against your blocks. Tools that do exactly this exist and they're not exotic. Faces are harder to reconstruct than text, but the principle holds: small blocks preserve information, and preserved information can be recovered.

My rules:

Faces and general shapes: big blocks, so big it looks chunky. If you can squint and recognize someone, it's too fine.
Sensitive text (bank numbers, IDs, addresses): honestly, use a solid bar instead of a mosaic. A black rectangle is ugly, but there's mathematically nothing left to recover. Pixelation on short text is fine if the blocks are huge relative to the character size.

The aesthetic mosaic look is for "this person didn't consent to be in my photo." For "this is my bank account number," destroy it completely.

Why doing this in your browser matters

This one bugs me about most "pixelate image online" sites: you have something so sensitive you're censoring it... so the site's first move is to upload the uncensored version to their server. Processed, maybe logged, maybe cached, on a machine you've never seen. You've leaked the secret in the act of hiding it.

A browser-based tool sidesteps that. The pixelation runs on your device's processor inside the tab. Don't take my word for it — open DevTools, watch the Network tab while you process. No image leaves.

Honest alternatives

Your phone's Markup tool (iOS Photos, Android editors) — free, already installed. You scribble or shape over things manually. Fine for one region; no proper mosaic control, and easy to leave a too-light cover.
Photoshop's Mosaic filter (~$23/month) — full control over cell size, perfect selections. Overkill if you just need a plate gone before posting a car for sale.
GIMP (free) — has Pixelize under Filters → Blur. Works, but it's a desktop install and the UI fights you the whole way.

For a 30-second censor job before sharing, the browser tool is the path of least regret.

FAQ

Can pixelated text be recovered? Sometimes, yes — if the blocks are fine, text can be reconstructed by brute-forcing characters through the same mosaic. Use very large blocks, or better, a solid bar for truly sensitive text.

How do I pixelate just one part of an image? Drag a selection box over the region in a pixelate tool and apply the mosaic only there. The rest of the image stays sharp.

Is it safe to pixelate sensitive documents online? Only if the tool runs in your browser without uploading. If the site processes images on a server, you've sent the uncensored document to a stranger.

What block size should I use to hide a license plate? Big enough that each character spans only one or two blocks. If any digit is still guessable, increase the size.

— Milo 🐨