Compress PNG images
Free, instant, and done right here — your photos never leave your device.
Lossless optimization
PNG is optimized losslessly — your pixels stay exactly the same.
Your photos never leave your device — everything happens right here in your browser.
How it works
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Drop your PNG files below — or tap to pick them
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They are optimized losslessly on your device — pixels stay exactly the same
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Download your smaller PNGs individually or all at once as a ZIP
PNG is a lossless format, which means every pixel is stored exactly as captured — no quality is ever discarded. That faithfulness comes at a cost: PNG files can be large, especially for screenshots, graphics, and images with flat areas of colour. What many people do not realise is that a PNG can be made significantly smaller without changing a single pixel. The file size reduction comes from choosing better compression parameters and stripping unnecessary metadata, not from throwing away image data.
imgAxe uses oxipng, a well-regarded open-source PNG optimiser, to do this work in your browser. oxipng tries multiple compression strategies and keeps the one that produces the smallest result. The pixels in the output file are mathematically identical to the pixels in the original — you could diff the two images pixel-by-pixel and find no differences. This is genuinely lossless: the only thing that changes is how efficiently the data is packed.
The amount of savings depends on how the original PNG was created. Screenshots saved by macOS or Windows, images exported from design tools like Figma or Sketch, and PNGs generated by code are often saved with fast-but-not-optimal compression settings. In those cases, oxipng routinely achieves 20–40% size reductions. Images that were already run through an optimizer will see smaller gains. If your PNG is a photograph, the savings tend to be more modest — and you should know that if file size is your main concern for a photo, converting it to JPG or WebP will reduce the size far more dramatically than lossless optimization ever can. We have a PNG to JPG and a PNG to WebP tool for exactly that.
All processing happens right in your browser. Your PNG files never leave your device — no server, no upload, nothing to sign up for. You can verify this yourself by opening the Network tab in your browser's developer tools while optimizing. There will be no outbound image traffic, just the local download when you are done.
Common questions
- Is this really lossless — will my image look different?
- No, the image will look identical. Lossless optimization changes how the pixel data is compressed and stored, but not the pixels themselves. You can open both files side by side and will not see any difference — because there is none.
- How much smaller will my PNG get?
- It depends on the source. Screenshots and design exports are often 20–40% smaller after optimization. Photos saved as PNG typically shrink less. Files that were already optimized may see only a small gain. If you need to shrink a photo dramatically, converting it to JPG or WebP is far more effective than lossless PNG compression.
- Do my files get uploaded to a server?
- No. Everything runs in your browser using your own device. Nothing is transmitted. Open the Network tab in your browser's developer tools during optimization and you will see zero outbound image traffic.
- Does it remove metadata like EXIF or color profiles?
- oxipng strips ancillary chunks that are safe to remove, including some metadata. If preserving specific metadata is important to you — for example, ICC color profiles for print work — check the output in a tool that reads those fields. For screen use, web publishing, and most everyday sharing, the stripped output is perfectly fine.
- Is there a file size or batch limit?
- imgAxe does not impose a limit. The ceiling is your device's available memory. Most modern phones and laptops handle batches of large PNG files without any trouble.