Are my images uploaded anywhere?

No. The compression runs in your browser using the Canvas API. The image never leaves your device, there is no server to upload to, and closing the tab discards everything.

Why did my file get bigger?

Re-encoding an already-optimised JPEG can increase its size, because the encoder cannot recover detail that was thrown away and may spend more bits describing the compression artefacts. The tool tells you when this happens instead of pretending it saved space — keep the original in that case.

Should I use JPEG, PNG or WebP?

JPEG for photographs. PNG for screenshots, logos and anything with sharp edges or transparency, because it is lossless. WebP is usually smaller than both at similar quality and is supported by every current browser.

Image Compressor — Shrink JPG, PNG & WebP In Your Browser, Free

Drop images here, or click to choose

JPG, PNG or WebP. Several at once is fine. Nothing is uploaded.

Quality — 80%

Lower means a smaller file and more visible artefacts. 80% is usually indistinguishable from the original.

Longest side (optional)

Resizes down to fit. Leave blank to keep the original dimensions. Never enlarges.

Output format

PNG is lossless, so the quality slider does not apply to it.

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Original

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Compressed

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Saved

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File	Before	After	Saved

Which format should you pick?

JPEG — photographs. Lossy, and the quality slider genuinely matters.
PNG — screenshots, logos, anything with sharp edges or transparency. Lossless, so the slider does nothing; the saving here comes from resizing.
WebP — usually smaller than both at the same visible quality, and supported by every current browser.

Why a file sometimes gets bigger

Re-encoding an already-optimised JPEG can grow it. The encoder cannot recover detail that was thrown away, and it can end up spending bits describing the previous compression's artefacts. When that happens this tool says so rather than reporting a triumphant 0% — keep your original.

Nothing is uploaded

The work happens in your browser through the Canvas API. There is no server to send images to, which is also why the tool is free and has no size limit beyond your own device's memory. Close the tab and everything is gone.