Image Compressor & Converter

How to use the Image Compressor

1. Drop a JPG, PNG or WebP onto the panel, or click it to choose a file.
2. Set Quality (default 80%). Optional: pick an output format (WebP, JPEG or PNG) and a max width or height in pixels.
3. Click Compress, check the original and compressed sizes, and preview the result.
4. Click Download when you are happy, or Start again to pick another file.

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What it is for

Web pages, email and messaging apps pay for every kilobyte. This tool redraws the image on a canvas in your browser and encodes it again, usually as WebP, so you can shrink a hero image, a product shot or an attachment that is too large to send. It is a practical compressor, not a lossless archive tool and not a batch studio.

Use it when you already have a single image and need a smaller file before upload. If you need a different format without worrying about size, choose Convert format at the top of the tool. For turning frames into a short animation, see the GIF Maker on the site.

Formats and transparency

JPEG has no transparency: a PNG with a transparent area will get a solid background (typically white) if you export to JPEG. WebP and PNG can keep an alpha channel. WebP is usually the best size for the web; PNG stays useful when you need crisp edges or transparency without WebP support in an older workflow.

Quality is the encoder’s quality setting (the slider shows a percentage label), not a promise that the file will be exactly that percentage of the original size. Lower quality and a smaller max edge cut more bytes; very high quality on an already-tight JPEG can sometimes grow.

Why it runs in your browser

Compression happens on your device. The file is not uploaded to Catpool. Close the tab and the image is gone from this page. That matters for unpublished photos, client work and anything you would rather not put on a random upload service.

Tips

• Start at quality 80 and only drop lower if the preview still looks fine for the use (web thumbnail vs print-ish preview).
• Set a max width or height when the source is a huge phone photo destined for a blog or product grid.
• Prefer WebP for most web use; keep PNG when you must preserve transparency without JPEG.
• One file at a time: this page is not a folder batch compressor.

Common questions

Why is the compressed file sometimes larger?

High-quality WebP of an already-tight JPEG can grow. Lower the quality slider, shrink the max edge, or try a different output format. The status line will say when a setting did not shrink the file.

Does quality 80 mean 80% of the pixels?

No. It is the encoder’s quality setting, not a size target and not “keep 80% of the pixels”. The pixel dimensions only change if you set a max width or height.

Can I compress a folder of images?

Not on this page. Choose one file, compress, download, then start again. For many files you would need a desktop batch tool.

Will JPEG keep transparent backgrounds?

No. Export to WebP or PNG if you need transparency. JPEG fills the transparent areas.

Is the original uploaded to Catpool?

No. Processing stays in the tab. Close the page and the file is gone from this tool.

What formats can I drop in?

JPG, PNG and WebP. Other types are outside what this page accepts.

Converting to another format

Press Convert format at the top, drop in a JPG, PNG, WebP, GIF or BMP, then pick JPG, PNG or WebP as the output. Quality starts higher (92%) because the aim is a different format, not a smaller file. You can still set a maximum width or height. JPG has no transparency, so transparent areas turn white; pick PNG or WebP to keep them.

Related: Create.