Image tool

Image Compressor

Shrink an image on this device with a quality slider, an optional resize, and an instant download. Nothing is uploaded.

Choose an image to see the compressed size here, then download the result.

Runs in your browser. Your entries are calculated on this device. Ziannah does not store the values you enter here.

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How it works

Compress an image without uploading it

Pick an image, choose a quality level and output format, and download the smaller file. The compression runs entirely in your browser using the canvas built into it, which is why no upload is needed.

Choosing a quality level

Between 70% and 85% is the practical sweet spot for photos: the file often shrinks by more than half before most people can spot a difference. Below 60%, compression artifacts start to show around edges and gradients.

JPEG, WebP, or PNG

JPEG is the safe default for photos. WebP usually produces the smallest file at the same quality and is supported by every modern browser. PNG is lossless, so the quality slider does not apply; use it only when you need transparency or exact pixels.

Resizing does the heavy lifting

Halving an image's width roughly quarters its pixel count, which shrinks the file far more than any quality setting. If a photo will be shown at 800px wide, there is no reason to ship 4000px.

Transparency and JPEG

JPEG has no transparency. When a transparent PNG is converted to JPEG here, the transparent areas are flattened onto white rather than turning black, which is the usual surprise with canvas conversion.

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