About ImagePress
本节目前仅提供英文版本。
ImagePress is a free image compression and conversion tool. It runs entirely in your browser: your images are decoded, compressed and re-encoded on your own device, and nothing is ever uploaded.
It was built because most online image compressors ask you to hand over your photos before they will shrink them. For a passport scan, a signed contract or a personal photograph, that is a poor trade.
Why everything runs locally
Modern browsers can decode and re-encode images using WebAssembly codecs — the same encoder implementations used by desktop software, compiled to run in a web page. Your image is read into memory in the tab, compressed there, and written straight back to your download.
Two consequences are worth stating plainly. There is no upload wait, so a large photograph starts compressing immediately. And there is no copy of your image anywhere but your own machine, so there is no retention policy to read and nothing to leak.
You can confirm this yourself: open your browser’s developer tools, watch the network tab, and compress an image. No upload request fires.
Formats and codecs
ImagePress supports the formats that matter for the modern web, and picks the right encoder for each job rather than forcing everything through one code path.
| Format | Compression | Transparency | Best for |
|---|---|---|---|
| WebP | Lossy or lossless | Yes | The safe default for the web |
| AVIF | Lossy or lossless | Yes | Smallest files for modern browsers |
| JPEG (MozJPEG) | Lossy | No | Photographs |
| PNG (OxiPNG) | Lossless | Yes | Screenshots, diagrams, flat graphics |
| JPEG XL | Lossy or lossless | Yes | Archival, very efficient |
| QOI | Lossless | Yes | Fast, simple lossless encoding |
How ImagePress is funded
ImagePress is free to use and supported by advertising on this site. Advertising pays for hosting and development. Because image processing happens locally, no advertiser and no ad network receives your images or anything derived from them — the ad code has no access to the content you are working on.
Advertising does involve third-party cookies set by the ad network. That is a separate question from image privacy and is covered in full in our privacy policy, including how to opt out.
Open source and attribution
ImagePress is built on Squoosh, the browser-based image compressor created by the Google Chrome team, which is licensed under the Apache License 2.0. The upstream licence is retained in the repository.
The individual codecs are separate open-source projects, each under its own licence — MozJPEG, OxiPNG, libwebp, libavif, JPEG XL and the resize and quantisation libraries among them. Their notices are kept alongside the code that uses them.
Languages
The interface is available in English, Simplified Chinese, Traditional Chinese, Japanese, Korean and Arabic. The language switcher is in the header, and your choice is remembered on your device.
Getting in touch
Bug reports, format requests and corrections are all welcome — see the contact page. If you have found a security problem, please say so explicitly.