画像圧縮

Smaller image files load faster, use less bandwidth and storage, and slip under the upload limits that email, forms and content systems impose. This compressor shrinks JPEG, PNG and WebP images while letting you decide how much quality to trade for size.

You set a quality level and, optionally, a maximum width or height. The tool re-encodes the image at that quality and resizes it if needed, then shows the before and after file sizes so you can see exactly how much you saved.

There are two ways it reduces size, and they stack. Re-encoding at a lower quality discards detail the eye barely notices (this is lossy, as used by JPEG and WebP), while resizing removes pixels outright. For a photo headed to the web, dropping to around 70 to 80 percent quality is often visually indistinguishable from the original.

Format matters. WebP typically produces noticeably smaller files than JPEG at the same visible quality, JPEG is the safe universal choice for photographs, and PNG is best for graphics, screenshots and anything needing sharp edges or transparency, though it compresses photos less efficiently.

Photographs shrink the most because their smooth gradients tolerate compression well; flat graphics and text are already small and gain less. If a result looks soft, nudge the quality back up; the savings curve flattens quickly past a certain point.

Crucially, the whole process runs in your browser. Your images are never uploaded, which makes this safe for private photos, ID scans or anything confidential, and means there is no waiting on a server.