How does PNG Crusher compress PNG files?

PNG Crusher uses median-cut colour quantization to reduce the number of colours in your image, converting 32-bit truecolour PNGs into indexed palette PNGs (PNG-8). You can choose from 256, 128, 64, 32, or 16 colours, with optional Floyd-Steinberg or ordered dithering to maintain visual quality.

How much can PNG Crusher reduce my file size?

Typical reductions range from 40% to 80%, depending on the image content and settings. Photographs with many colours see the largest savings when reduced to 256 colours. Images with flat colours or limited palettes may already be well optimised.

Can I compress multiple PNG files at once?

Yes. PNG Crusher supports batch processing. Drag and drop or select multiple PNG files at once, configure your settings, and compress them all in one go. You can download each file individually or all at once.

Compress PNG Online Free — Reduce PNG File Size up to 80%

📦

Drop PNG files here

or click to browse · supports multiple files · max 50MB each

All Files

Filename	Savings	Action

Free Online PNG Compressor

PNG Crusher is a free, privacy-first image compression tool that shrinks your PNG files directly in the browser. Unlike server-based compressors, every byte stays on your device, making PNG Crusher ideal for sensitive screenshots, proprietary artwork, and confidential documents.

The tool uses median-cut colour quantization to convert 32-bit truecolour PNGs into compact indexed-colour PNGs (PNG-8). This technique reduces the colour palette to as few as 16 colours while preserving visual fidelity through advanced dithering algorithms. The result is typically a 40–80% reduction in file size with minimal perceptible quality loss.

How PNG Compression Works

PNG files use lossless DEFLATE compression, meaning no pixel data is discarded during encoding. However, files with millions of unique colours produce much larger DEFLATE streams. By reducing the palette to 256 or fewer colours, the image can be stored as an indexed PNG with a compact colour table, dramatically shrinking the file.

PNG Crusher offers three dithering modes to control how colour reduction appears. Floyd-Steinberg error-diffusion dithering distributes quantization error to neighbouring pixels, producing smooth gradients that closely match the original. Ordered dithering uses a Bayer matrix for a fast, patterned result. No-dithering mode maps each pixel to its nearest palette colour, ideal for flat-colour graphics, logos, and UI elements.

Batch PNG Compression

Need to compress multiple PNG files at once? PNG Crusher supports full batch processing. Drag and drop an entire folder of PNGs, configure your settings once, and compress them all in a single pass. A detailed results table shows the original size, compressed size, and percentage savings for every file. You can download files individually or grab them all at once.

Before-and-After Comparison

Every compressed image gets a live side-by-side comparison slider so you can inspect quality before downloading. Drag the slider left and right to compare the original against the compressed version at pixel level. This lets you fine-tune your colour depth and dithering settings until you find the perfect balance between file size and visual quality.

When to Use PNG Crusher

PNG Crusher is perfect for web developers optimising page load times, designers preparing assets for email campaigns, bloggers shrinking header images, and anyone who needs smaller PNG files without installing desktop software. It works on any modern browser — Chrome, Firefox, Safari, Edge — on desktop and mobile, with no plugins or extensions required.

Frequently Asked Questions

Is PNG Crusher really free?

Yes, completely free with no limits on file count or size. There are no watermarks, no sign-up, and no premium tier. If you find it useful, you can leave an optional tip via the donate button.

Are my images uploaded to a server?

No. PNG Crusher runs 100% client-side using JavaScript. Your images are processed in your browser's memory and never leave your device. There is no server-side code, no analytics on your images, and no data collection of any kind.

How much smaller will my PNG files be?

Most photographs and complex images see a 50–80% reduction at 256 colours with Floyd-Steinberg dithering. Simple graphics with few colours may already be well optimised and see smaller gains. The comparison slider lets you check quality before committing.

Does compression affect transparency?

By default, PNG Crusher preserves the alpha channel. If your image is fully opaque, ticking "Strip alpha channel" removes the transparency data and can squeeze out additional savings.

What browsers are supported?

Any modern browser with JavaScript enabled — Chrome, Firefox, Safari, Edge, Opera, and Brave on both desktop and mobile devices.