compresso.

Reduce image size without losing quality

Shrink file size while the picture stays visually identical to the original — guaranteed by a per-pixel quality check, not a promise.

Identical to the original, verified pixel by pixel

Most compressors make you trade quality for size: push a slider and hope the result still looks acceptable. Compresso works the other way around. For every image it produces a compressed candidate, then compares it with the original pixel by pixel. If the difference could be noticed by eye, that candidate is rejected and a safer one is kept. Your image is never returned worse than it went in.

For PNG we use palette quantization — the same family of techniques behind professional tools — gated by that visual check. For JPEG we re-encode with mozjpeg, the most efficient open JPEG encoder available. Typical results are 50–80% smaller for PNG and around 70% for JPEG, with no visible difference on screen or in print.

Everything runs on our server in memory and is deleted the moment your download is ready. Nothing is stored, logged or shared. Drop up to 20 images at once, download them one by one or as a single ZIP.

Frequently asked questions

Is this really lossless?
It is visually lossless: the result is indistinguishable from the original to the human eye. For PNG, where a truly identical copy is smaller, you get an exact lossless file; for photos a tiny, imperceptible change buys a much smaller file. Compresso never keeps a version that looks worse than the original.
Which formats are supported?
PNG, JPEG and WebP. Each is compressed with the encoder best suited to it and checked against the original before you download.
Do you keep my images?
No. Files are processed in memory and removed as soon as the compressed copy is sent back. They are never written to disk, logged or shared.
Is there a file limit?
Up to 20 images per batch, 25 MB each. There is no daily cap and no sign-up.

More tools

All formatsCompress PNGCompress JPEGCompress WebP