How to use
- Drop your images onto the box above, or click it to choose files. You can add several at once.
- Adjust Quality — lower means a smaller file and more visible artifacts.
- Optionally pick an Output format or cap the Max dimension to shrink oversized photos.
- Each file shows its before and after size. Click Download, or Download all when you are done.
Changing any setting re-compresses everything already in the list, so you can dial in the quality you want and watch the file sizes respond.
About image compression
Most of the weight on a slow-loading page is images, and most of that weight is avoidable. A photo straight out of a phone camera is often 4–6 MB at 4000 pixels wide — but it will be displayed in a 800-pixel-wide column, where all but a fraction of those pixels are thrown away by the browser after being downloaded. Resizing before uploading usually saves more bytes than any amount of quality tuning.
JPEG and WebP are lossy: they discard information the eye is least likely to notice, particularly fine colour variation, and the quality setting controls how aggressively. The loss is permanent and it compounds — re-compressing an already-compressed JPEG degrades it again, which is why you should always work from the original rather than repeatedly saving the same file.
PNG is lossless, so the quality slider does not apply to it. It stores exact pixel values, which makes it the right choice for screenshots, diagrams, logos and anything containing text or sharp edges, where JPEG’s artifacts are obvious. It is the wrong choice for photographs, where it produces files several times larger than JPEG for no visible benefit.
One consequence of JPEG having no transparency channel: converting a PNG with a transparent background to JPEG has to fill that background with something. This tool fills it with white, which is the usual expectation — but if you need the transparency, keep the file as PNG or WebP.