About img-compress

Why this site exists

Most “free online image compressor” tools work the same way: you hand your photos to a server you know nothing about, it processes them, and you download the result. That is fine for a screenshot of a spreadsheet. It is a worse deal for a passport scan, a medical report, a photo of your kids, or a product shot that isn't public yet — and there is usually no way to find out how long the file sticks around afterwards.

Browsers have been able to decode, resize and re-encode images locally for years. img-compress is built on that: the file is read from disk into the page, processed by your own CPU, and written back out as a download. Nothing crosses the network, so there is nothing to retain, leak, or hand over.

How it works

When you drop a file in, the browser decodes it into a bitmap, redraws it onto a canvas at the size you asked for, and re-encodes it to JPG, PNG, WebP or AVIF at your chosen quality level. The quality slider maps directly to the encoder's quality parameter, so what you set is what the encoder gets.

Batches are processed one file at a time in the same tab and zipped locally when you pick the ZIP download, so a folder of 200 photos never becomes 200 network requests. You can verify all of this yourself: open your browser's developer tools, switch to the Network tab, and compress something — you will not see a single upload.

What it can't do

Running locally has real trade-offs, and it seems more useful to state them than to hide them. Very large files are limited by how much memory your browser gives a single tab, so a few hundred multi-megapixel images at once will be slower than a server farm would be, and phones tap out sooner than desktops.

HEIC and HEIF files from an iPhone only decode in Safari. Chrome, Edge and Firefox don't ship an HEVC decoder, and shipping our own would mean bundling a patent-encumbered codec into the page — so on those browsers the HEIC converters tell you up front instead of failing halfway through.

PNG is a lossless format, so the quality slider has far less effect on a PNG-to-PNG job than it does on JPG, WebP or AVIF. Where a PNG is genuinely oversized, converting it to WebP or JPG is what actually shrinks it, and the converter pages say so.

Who is behind it

img-compress is an independent project, built and maintained by one person — Antonio Jaime — rather than a company. There is no team inbox, no support tier and no investors behind it: mail sent to the address below is read by the person who writes the code.

It is not a wrapper around somebody else's API either. The compression runs on standard browser APIs, the site is built with Next.js and served from the edge, and the guides on the blog are written for this site rather than syndicated or reassembled from other people's articles.

How it pays for itself

The site is free and has no accounts, no watermarks, no file-size caps and no “pro” tier. It is funded by advertising, which is the only thing on the page that involves a third party at all.

Advertising is also why the cookie banner exists: advertising and analytics cookies are opt-in wherever the law requires consent, and you can change your choice at any time from the link in the footer. Your images are never part of that — they are not uploaded, so there is nothing about them to share with anyone, advertisers included.

The guides

Alongside the tool there is a small library of guides on image formats: what AVIF actually saves over WebP, why an upload form rejects an iPhone photo, when PNG is the wrong choice. They are written to answer the question and then stop, and they get corrected when they turn out to be wrong. If you find an error in one, please say so.