Make PNG files smaller
PNG is lossless: every pixel is stored exactly, which is why screenshots, logos and graphics are saved as PNG, and why the files get large. There are two ways to shrink them.
Fewer colours (the big saving). Most screenshots and graphics look the same with 256 colours or fewer. The compressor picks the best palette for each picture (with our own colour quantiser), maps every pixel to it with gentle dithering so gradients don't show bands, and keeps transparency, including soft half-transparent edges. This often makes a PNG several times smaller.
Lossless optimisation. The pixels stay exactly the same, but the PNG is re-compressed with better row filters, smaller colour types where the picture allows, and a stronger deflate encoder (oxipng). This saves less, but changes nothing.
Both are applied: a picture is reduced to fewer colours and then optimised, and it is only reduced when that actually makes it smaller.
How to use it
- Upload PNG files or a ZIP of a folder.
- Keep “Up to 256 colours”, or choose fewer colours for even smaller files, or “Keep all colours” for lossless optimisation only.
- Click Compress.
When to keep all colours
- Photos saved as PNG have many subtle shades; fewer colours can show grain. For photos, saving as JPEG, WebP or AVIF is usually the better choice, and much smaller.
- Pictures you will edit again, medical or scientific images, and 16-bit PNGs should stay lossless.
Animated PNGs (APNG) are optimised losslessly, frame by frame, and stay animated. Metadata such as text comments and EXIF is removed by default; the colour profile is kept.
More about what this tool reads and writes: Image Compressor.