How to compress images online without losing quality (batch, browser-based)

Why compress images?

Large image files slow down web pages, fill up storage, and get rejected by upload forms. Compression trades a small amount of visual quality for a significantly smaller file — often 40–80% smaller with little perceptible difference at typical screen sizes.

Lossy vs lossless

• Lossy (JPEG, WebP): discards image data that the eye barely notices. A quality setting of 70–80% usually looks near-identical but cuts size in half.
• Lossless (PNG, SVG): stores every pixel exactly. These formats do not support a quality parameter — they are exported as WebP here so the quality slider actually has an effect.

Which quality setting should I use?

Start at 70% and work down until the balance suits your use case.

Workflow

1. Open Image Compressor.
2. Drag up to 10 images onto the drop zone, or click to browse. Supported: JPG, PNG, WebP, GIF, BMP, TIFF, SVG.
3. Adjust the quality slider (5–95%). The same setting applies to all files in the batch.
4. Click Compress — all files are processed in parallel in your browser.
5. Check the size reduction shown for each file (e.g. "63% smaller").
6. Download files individually, or click Download all when two or more are ready.

SVG and PNG notes

PNG is a lossless format — there is no "JPEG quality" equivalent. SVG is a vector format. When either is added to the compressor, the tool re-encodes to WebP, which supports transparency and a quality parameter. The output file name will end in .webp.

If you need to keep the PNG format, use a dedicated lossless PNG optimiser (such as pngcrush or Squoosh) instead.

Privacy reminder

Everything runs locally in your browser tab. Your images are never uploaded to a server. You can disconnect from the internet after the page loads and compression will still work.

Related tools

• Image to WebP — convert format without the quality slider workflow.
• PDF Compressor — same quality-based approach for PDFs.