Compress PNG Online — Free, Fast & Private
PNG (Portable Network Graphics) is the go-to format for screenshots, logos, icons, graphics with text, and any image that requires transparency. Unlike JPEG, PNG uses lossless compression — which means perfect quality but significantly larger file sizes. A single PNG screenshot from a modern display can easily reach 2-5 MB.
MiniPx compresses your PNG files directly in your browser using the Canvas API and smart multi-pass compression. The algorithm tries multiple quality levels automatically and picks the smallest output that maintains visual quality. For maximum file size reduction, you can output as WebP format — which supports transparency just like PNG but typically produces files 25-35% smaller.
What makes MiniPx different from tools like TinyPNG or Compressor.io? Privacy. Those tools upload your images to remote servers for processing. MiniPx runs entirely client-side — your PNG files never leave your browser. This matters if you are compressing screenshots containing sensitive information, proprietary designs, or personal photos.
MiniPx also supports batch PNG compression — 5 files per batch on the free tier, uncapped with Pro — with the whole batch downloadable as a ZIP. For web developers optimizing site performance, this means faster Core Web Vitals scores and better Google rankings without exposing your assets to third-party servers.
For designers working with PNG assets for apps and websites, the recommended workflow is: compress with the Smart preset first, check the output quality, then switch to Tiny only if you need further reduction. If transparency is not needed, converting to JPEG will give the smallest possible file size. When a format change is what you actually need, the PNG converter handles conversion to and from PNG. And if the PNG in question is a logo headed for a browser tab, the favicon generator renders it at every icon size — with the outputs already run through this compressor's PNG encoder.
How to reduce PNG file size without losing quality
The key to shrinking a PNG is understanding what makes it large in the first place. PNG files store every pixel as raw colour data, which means a 1920×1080 screenshot can easily exceed 3 MB. MiniPx reduces this by re-encoding the image through the Canvas API at optimised quality levels. The Smart preset analyses the image content and picks the lowest quality setting that produces no visible difference — typically cutting file size by 50-70%. For logos, icons, and graphics with flat colours, the reduction can reach 80%. And when the PNG carries more pixels than its destination shows — a retina screenshot dropped into a doc, say — resize the PNG first: for a lossless format, dimensions are the bigger lever, and the compressor then works on only the pixels you kept.
If you need even smaller files, convert your PNG to WebP format. WebP supports lossless compression and transparency — just like PNG — but produces files that are 25-35% smaller. Every major browser now supports WebP, including Safari 14 and above. MiniPx lets you switch the output format with one click, so you can compare PNG and WebP output sizes side by side.
Compress PNG online for websites and apps
Page load speed directly affects your search ranking. Google uses Core Web Vitals as a ranking signal, and large PNG images are one of the most common causes of slow Largest Contentful Paint (LCP) scores. Compressing your PNGs before uploading them to your site can cut page weight by megabytes without any visible change to your visitors.
For web projects, the most effective workflow is: compress all PNG assets in MiniPx using the Smart preset, then convert any PNGs that do not require transparency to JPEG or WebP. This two-step process can reduce your total image payload by 60-85%. MiniPx handles batch processing — drag in your entire assets folder and download the compressed versions as a single ZIP file.
Shrink PNG files on your phone
MiniPx works on any phone browser — iPhone Safari, Android Chrome, Samsung Internet. There is no app to download and no account to create. Open minipx.com, select your PNG files from your photo library or Files app, compress, and save the smaller versions back to your device. This is useful for compressing screenshots before sharing them on WhatsApp, Slack, or email — where large PNG files can be slow to send and waste the recipient's mobile data.
PNG is lossless in the strict sense — bit-for-bit identical after a round trip. what lossless actually guarantees explains why that puts a hard floor under how small a PNG can get.