Image compressor

What it does

Resize an image manually or compare JPEG and WebP at the same dimensions against a target byte size.

How to use it

1. Choose a JPEG, PNG or WebP up to 20 MiB. Manually adjust width and quality, or keep dimensions fixed and compare JPEG/WebP candidates against a target from 100 bytes to 20 MiB.
2. WebP supports transparency. JPEG puts transparent areas on white. Animated PNG and WebP are rejected; original metadata is not retained.
3. The comparison measures at most ten candidates per codec and shows whether each meets the budget. Inspect both previews and sizes; the search does not guarantee the best possible quality or a successful fit.
4. Manual resizing accepts up to 40 megapixels. Fixed-dimension comparison accepts up to 16 megapixels and 8,192 pixels per side, with a cancellable 30-second deadline. Browser codec support and image content affect results.

Example

Compare a 1,200 × 800 image as JPEG and WebP against a 100,000-byte budget, inspect the measured quality candidates and preview both outputs before downloading.

Methodology

Manual mode uses Canvas to resize without upscaling and encode JPEG or WebP. Fixed-dimension comparison runs in a local worker, testing quality endpoints and a bounded search of at most ten measured candidates per codec. It returns the highest-quality measured candidate within the budget, or the smallest measured candidate when none fits; this is not an exhaustive optimum.

Limitations

20 MiB JPEG/PNG/WebP input with bounded signature/dimension checks before decode and post-decode verification; animated PNG/WebP and unsupported headers are rejected. Manual resizing up to 40 MP with output sides at most 8,192 pixels. Fixed-dimension comparison up to 16 MP / 8,192 pixels per side, target 100 bytes–20 MiB, ten attempts per codec, 64 MiB per encoded candidate and a cancellable 30-second deadline. Requires browser WebP/JPEG worker encoding support. File size can increase or remain above target. WebP preserves supported transparency; JPEG flattens it onto white. Original metadata is not retained; visual quality and browser encoding differ.

Automation

This tool runs in your browser. No upload API or MCP endpoint is available.