Zellio.io

Image Compressor

Shrink PNG & JPEG files to a target size — one at a time or in batches.

Runs locallyWorks offlineShare link carries settings, never your data
Send output toWatermark AdderMeme GeneratorEXIF Viewer & RemoverBuild a workflow from thisOutput stays on this page until you send it.

Frequently asked questions

Are my photos uploaded to compress them?

No. Everything runs locally in your browser using standard web APIs — your text, files and inputs are never uploaded to a server, so the tool works even offline once the page has loaded.

How many images can I do at once?

Twenty per batch. Each one is held as both its original bytes and a decoded bitmap, so twenty phone photos is already several hundred megabytes of tab — beyond that the page slows down and eventually risks taking the whole batch with it. Nothing limits how many batches you run, and none of it is metered.

Will compression hurt image quality?

JPEG uses lossy compression, so very aggressive targets can soften detail, but moderate settings shrink files substantially with little visible change. PNG stays lossless. For photographs, JPEG compression at 75-85% quality typically achieves a 50% file size reduction with imperceptible quality loss to human eyes. PNG is better for graphics, logos, and images with sharp edges where any quality loss is visible, though lossless compression yields smaller files than uncompressed formats. Experiment with moderate compression levels first, then preview the result to ensure it meets your quality standards before downloading.

What size should I aim for?

For web pages, most photos look great well under 200 KB. Lower the target for thumbnails and raise it for hero images that need more detail. A 100-150 KB JPEG is ideal for product images in e-commerce, while 200-400 KB works well for full-width hero images on homepages. Social media platforms like Instagram and Facebook automatically compress uploads, so files under 200 KB rarely need further optimization before posting. For email attachments, aim for 50-100 KB to stay within typical inbox size limits. Consider using WebP format, which often achieves 20-30% better compression than JPEG at the same quality level.

Pro tips

  • Select or drop several images at once — they all aim at the same target, and Download all saves each one under its own source name rather than a pile of files called the same thing.
  • PNG has no quality dial, so the PNG option can only reach a target by reducing the dimensions. Choose JPEG or WebP to keep the full resolution.
  • WebP typically lands 20-30% below JPEG at the same visible quality, so switching format is often a bigger win than pushing the target down.
  • Each result says how it got there — the quality the search settled on, or the scale a PNG was reduced to. If it could not reach the target it tells you that instead of quietly missing it.

About Image Compressor

Aim at a file size rather than guessing at a quality percentage — set the target and the tool works toward it. That is the difference between meeting an upload form's 2 MB cap first time and trying quality settings until one sticks.

Reduce the file size of PNG and JPEG images toward a target size while keeping them web-ready. Smaller images load faster, improve Core Web Vitals and save bandwidth without a visible drop in quality for most photos.

Drop in a folder's worth at once. Up to twenty pictures share one target and one Download all, each listed against the weight it started at and named after the file it came from. Anything already lighter than the target is handed back untouched — re-encoding a picture that is done makes it bigger, not smaller.

Compression is not uniformly effective, because it depends entirely on what the picture contains. A photograph of foliage, gravel or crowd detail compresses poorly — there is genuine information in almost every pixel — while a clear sky, a studio background or a flat graphic compresses enormously. That is why one image drops to a tenth of its size at a quality setting another barely responds to, and why targeting a fixed file size takes several encoding passes to converge rather than a single calculation.

Common use cases

  • Web developers optimizing product images for e-commerce sites to improve Core Web Vitals scores and SEO rankings.
  • Content creators putting a batch of social media images through one target to stay within platform upload limits and improve load times.
  • Mobile app developers reducing APK size by compressing hundreds of in-app images and asset bundles.
  • Email marketers compressing promotional images to stay within 25MB email size limits while maintaining brand quality.
How it comparesUnlike TinyPNG which charges $0.80-2.00 per 500 images after free tier, our compressor takes twenty to a batch and as many batches as you like at no cost, offering more control than Compressor.io's auto-only approach while supporting more formats than ImageOptim.