Large images slow websites, get rejected by email, and fill storage. The good news: you can reduce most images by 60–80% with no visible quality difference.
What quality setting should I use?
70–80% is the sweet spot for web use. The human eye can't detect the difference, but the file is 5–10× smaller. For print, use 90%+.
Lossy vs lossless compression
Lossy (JPEG): throws away some data permanently. Great for photographs. Lossless (PNG, WebP): compresses without data loss. Better for graphics, logos, screenshots.
How to compress in 3 steps
Go to Compress Image. Upload your file. Set quality to 75%. Download. Everything runs in your browser — no upload, no privacy risk.