CodeKitHubWhat Is This Tool?
PNG is lossless, so it has no "quality" setting to lower — naive re-encoding barely helps. Real PNG compression works differently: palette quantization reduces the image to a carefully chosen set of colors (up to 256). Since screenshots, logos and interface graphics rarely use more distinct colors than that anyway, the file gets 50–70% smaller while looking identical. Transparency (the alpha channel) is fully preserved.
This is the technique behind well-known services like TinyPNG — the difference here is that it runs in your browser via an open-source engine, so your images stay on your device and there's no daily file limit.
Why Use It?
- Real compression (50–70% typical), not a placebo re-encode.
- Transparency preserved — safe for logos, icons and UI assets.
- No upload, unlike TinyPNG-style services — and therefore no file count limits.
- Adjustable color budget (16–256) with per-image savings shown.
- Batch support, free, no watermark.
How to Use
- Drop PNG files onto the box (the compression engine loads automatically, once).
- Keep 256 colors for visually identical results, or lower it for smaller files.
- Each result shows the exact savings — click Download.
- If a photo-like PNG doesn't shrink enough, convert it to JPG instead (see PNG to JPG).
Example
Input
app-screenshot.png — 980 KBOutput
app-screenshot-compressed.png — 290 KB (−70%), 256 colorsScreenshots and UI graphics quantize beautifully; the palette covers every color they actually use.
From our own testing
Our launch test used a deliberately hostile image: a 600×400 PNG filled with 200 overlapping semi-transparent color patches — far messier than a typical screenshot. It quantized from 31.1 KB down to 7.8 KB (−75%) at 256 colors, with the alpha channel intact. Real-world UI graphics compress even better because they use fewer distinct colors than our stress test. The honest flip side we also confirmed: photographic content shows visible banding at 256 colors — that's when you want the JPG/WebP route instead, which is why the converter links sit one section up.
Frequently Asked Questions
How can a lossless format be compressed further?
By making it slightly lossy in a smart way: quantization picks the ~256 colors that best represent the image and maps every pixel to them. For graphics with limited color ranges the result is visually identical — technically lossy, practically indistinguishable.
Will transparency survive compression?
Yes — the alpha channel is preserved, including semi-transparent pixels (drop shadows, anti-aliased edges). This is exactly what logos and UI assets need.
When does PNG compression work poorly?
On photographs and smooth gradients — they use thousands of colors, so 256 can show banding. For photo content, converting to JPG or WebP saves far more; that's what our PNG to JPG converter is for.
How is this different from TinyPNG?
Same underlying technique (palette quantization), similar savings. The practical differences: your files are never uploaded here, there's no 20-file batch limit, no 5 MB cap, and no paid tier — because there's no server doing the work.
What color count should I choose?
Start at 256 — visually identical for nearly all graphics. Drop to 64 or 32 for icons and simple UI elements to squeeze more; watch the preview thumbnail for banding.