Compress PNG images losslessly — in your browser
Drop a PNG and Tinier optimizes it locally on your device with OxiPNG, a Rust-based PNG optimizer that re-encodes pixel data without changing a single pixel. Typical savings are 10–20% on real-world PNGs — modest, but actually lossless. Nothing uploads. Up to 50 MB per file, 1 to 10 files at a time.
What "lossless" really means for PNG
Lossless compression makes a file smaller without changing its contents — decompress it and you get back exactly what you started with, pixel for pixel. OxiPNG achieves this by trying different filter and compression strategies and keeping the smallest encoding that reproduces the image perfectly. It also strips metadata the image does not need. What it never does is touch the actual pixels. That is the honest definition of lossless, and it is the only kind of PNG compression Tinier does.
When PNG cannot be made smaller
Some PNGs are already optimized — exported by a tool that ran the same kind of pass Tinier does. When that happens, Tinier tells you the file is already optimized instead of pretending to have helped or, worse, saving a slightly larger file. A photo saved as PNG is another case: photos have millions of subtly different colors, which PNG stores inefficiently. If your PNG is really a photo, converting it to JPG or WebP will save far more than lossless PNG optimization ever could.
The slider controls effort, not quality
On JPG and WebP the slider trades quality for size. On PNG there is no such trade — the pixels are always preserved. The PNG slider controls how hard OxiPNG works to find a smaller encoding. Higher effort can find a few extra percent of savings at the cost of taking longer. Either way the image that comes out is identical to the one that went in.
Why compress PNG in the browser instead of on a server?
Most online PNG compressors upload your file to a server. Many of them also quantize the palette and call the result "lossless" — it is not. Tinier runs OxiPNG locally in your browser via WebAssembly, so your file never leaves your device, and it stays genuinely lossless. You can disconnect your internet after the page loads and it keeps working. Privacy here is structural, not a promise in a policy.
Frequently asked questions about PNG compression
Is PNG compression really lossless?
Yes. OxiPNG re-encodes the pixel data and strips redundant metadata without changing a single pixel. The output is bit-for-bit identical in appearance to the input. Some other tools claim "lossless" but quantize the palette, which is not lossless — Tinier never does that.
Why does my PNG only compress 10–20%?
Because that is what lossless PNG compression actually achieves on real-world images. The larger numbers you see elsewhere (50%+) come from quantization, which reduces the color palette and changes the image. Tinier keeps it truly lossless, so the savings are honest and modest.
What does the slider control on PNG?
Optimization effort, not quality. A higher setting makes OxiPNG try harder to find a smaller encoding, which takes longer but never changes the image. There is no quality trade-off on PNG — the pixels are always preserved exactly.
Can Tinier compress PNG with transparency?
Yes. The alpha channel is preserved exactly, like every other pixel. Transparent and semi-transparent PNGs compress the same way as opaque ones.
Other formats Tinier compresses
- Compress JPG — lossy compression with MozJPEG and a real quality slider.
- Compress WebP — Google's modern image format, in your browser.
- PNG to WebP — convert PNG to a smaller WebP, transparency kept.
- Image compressors compared — an honest look at where Tinier wins and where it does not.