- Does my image get uploaded anywhere?
- No. The blur runs entirely in your browser on a canvas — the file is read from your disk, redrawn, and encoded without a single byte going to a server. You can check this yourself: open your browser's network panel, drop an image in, and watch nothing happen. That matters more here than on almost any other tool, because the whole reason you are blurring something is that you do not want it seen. Most of the free online blur sites in this category upload the photo to a server to do the work, which means the document you are censoring gets handed to a stranger's machine first. Close the tab and this one is gone.
- Can someone un-blur the image afterwards?
- Not from the file you download here. The blur is applied to the pixels and the result is flattened into a normal raster image — there is no original layer underneath, no CSS filter sitting on top, no second image stream hiding in the container. What gets saved is what you see. That is not true of every method people use: a blur applied in a design tool and exported to a layered format, or a black box drawn over text in a PDF, often keeps the original underneath and can be pulled back out. If you want mathematical certainty rather than a very strong practical guarantee, crop the sensitive part out of the picture entirely.
- How strong does the blur need to be?
- Stronger than you think, if you are hiding text. A gentle blur smooths the edges of letters without destroying the shapes, and a determined reader — or a piece of software — can often still make out a street number or the last four digits of a card. The rule of thumb is to push the slider until you genuinely cannot tell what was there when you look at the preview at full size. The tool warns you when you have drawn a region and left the strength low enough that the content underneath may still be readable, but it does not stop you downloading — sometimes a soft blur is the effect you want, and that is your call to make.
- Why does the same slider position look different on my two photos?
- It shouldn't, and that is the point of how the strength works here. Most tools in this category use an absolute pixel radius, so 10 wipes out a small thumbnail and is almost invisible on a large phone photo. This one derives the radius from the image's shorter side, so the same slider position produces the same visual result whatever you feed it. If the blur looks weaker on one picture, it is because that picture is a different shape, not a different size — a very wide panorama takes its radius from its height, deliberately, so the blur doesn't swallow the whole strip.
- What's the difference between blur and pixelate?
- Blur smears the pixels together into a soft gradient; pixelate averages them into visible square blocks. Practically they hide the same amount of information at the same strength, so it comes down to how the result reads. Blocks look deliberate — nobody mistakes a pixelated face for a photo that came out badly — which is why news and documentary work tends to prefer them. A blur is quieter and blends into a screenshot more naturally. Both are driven by the same slider here, so you can flip between them and compare without losing your place.
- Does blurring remove the location data from my photo?
- Yes, as a side effect, and it is a bigger deal than most people realise. Photos taken on a phone usually carry EXIF metadata including precise GPS coordinates, the device model, and the timestamp. Blurring the house number in the picture does nothing about the coordinates sitting in the file's header — the address is still right there for anyone who opens the properties panel. Because this tool re-encodes the image through a canvas, none of that metadata survives into the download. The file you get out carries the pixels and nothing else.
- Can I blur a face automatically?
- No, and that is a deliberate choice rather than a missing feature. Automatic face detection misses faces at an angle, in shadow, or partly behind something, and a tool that quietly misses one is worse than a tool that never claimed to find them — you would post the picture believing it was handled. Dragging a box takes about two seconds and you can see exactly what you covered. If you have several faces to hide, draw several boxes; they are additive and you can undo them one at a time.
- Why won't it open my iPhone photo?
- Because iPhones save in HEIC, and no browser can decode HEIC for an arbitrary file — not Chrome, not Firefox, not even Safari. The tool sniffs the file header rather than trusting the extension, so a HEIC that has been renamed to .jpg gets caught too, and it points you at the HEIC to JPG converter instead of failing with something vague. Convert first, come back, and the JPG works normally. You can also skip the round trip for good: iOS Settings, Camera, Formats, Most Compatible makes the phone shoot JPG.
- What happens to a PNG with a transparent background?
- The transparency survives. The blur is drawn onto a transparent canvas rather than composited over white or black, so a cut-out subject stays cut out in the downloaded file. This is a place where a lot of blur implementations quietly go wrong — blurring near an edge pulls in the pixels beside it, and if those pixels are an assumed background colour you get a grey or black halo around the transparent part. The whole image is blurred into its own buffer first and then composited, which is also what stops a hard edge appearing around the boxes you draw.
- Why don't I have to sign in?
- Because blurring one thing out of one picture is not worth an account. The usual pattern in this category is a full photo editor that opens a project, offers you blur as one filter among hundreds, and then asks for an email before it will let you export — or puts a watermark on the result and a resolution cap on the free path. There is no sign-up here, no watermark, no export gate, no cap, and no limit on how many images you run through it.
