About FileBelow
FileBelow exists because of a specific, extremely common moment: you have been rejected by an upload form. It told you the file must be under 2 MB, or at least 1600 pixels wide, or a JPG, and then offered no way to comply. You did not want to learn about image compression today.
The limit is the input
Most tools for this hand you a quality slider and let you guess your way toward the number. You export, check the size, adjust, export again. The number you actually care about — the one the form gave you — never appears anywhere in the process.
FileBelow starts from that number. You type in what the file needs to be and it produces the best-looking image that meets it. That inversion is the entire point of the product.
How it decides what to give up
A photograph’s file size depends on two things: how many pixels it has, and how hard the encoder compresses each one. Nearly every other tool varies only the second, which at tight limits produces the blocky, smeared look everyone recognises.
FileBelow searches both. It encodes candidates at several resolutions, finds the highest quality that fits your limit at each one, and then compares every candidate against your original using a structural similarity measure. The one that scores highest wins — which is often not the largest.
On our test photographs, at a 100 KB target, this scores substantially better than a quality-only search at the same size. Below about 50 KB, a quality-only search at full resolution cannot reach the target at all, while this approach still can. The result panel shows the dimensions it chose, so the trade is visible rather than hidden.
Nothing is uploaded
All processing happens in your browser, on your device. There is no server that could receive an image, because the site is entirely static. This is not primarily a privacy stance — although it is a good one — so much as the correct architecture: browsers can already decode and encode images, so sending a photograph across the internet and back to do it is slower and worse for everyone.
A side effect worth knowing: because the image is re-encoded on your device, the EXIF metadata — including the GPS coordinates of where the photo was taken — does not survive into the file you download.
About the destination requirements
The site lists image requirements for a small number of specific platforms. Every one was read off that platform’s own documentation, and every page shows the link and the date it was checked.
The list is short on purpose. It would be easy to publish sixty destinations and be wrong about half of them, and someone whose passport photo or product listing is rejected on our say-so has been actively harmed. Where a platform publishes dimensions but no size limit, we list the dimensions and leave the rest blank rather than inventing a plausible number.
What it costs
Nothing. There is no account, no upload quota, no watermark and no paid tier. We may add advertising to help cover hosting; if we do, it will never be placed where it can be clicked by accident while you are using the tool, and the privacy page will be updated before it appears.
Found a bug, or a requirement we have got wrong? Get in touch — particularly for the requirements, where being wrong has real consequences for whoever trusted the page.