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Compress PNG

Compress PNG images to a size in KB, keeping transparency and sharp edges. Many at once, free, with no upload.

Files stay on your device

Drop images to get them under 100 KB

Add one or as many as you like. Each is compressed on your device until it fits, so nothing is uploaded.

PNG, JPG, WebP, HEIC, AVIF, SVG, BMP, and GIF. As many as you like, or a whole folder.

Compress to
Each picture is saved at the highest quality that fits, then drawn smaller when quality alone can't get it there.

A picture already under it is kept as it is.

Keeps transparency and sharp edges. A large PNG is cut to 256 colors to fit.

Off, the quality goes as low as it takes instead, and some sizes can't be reached.

How to compress a PNG online

Type the largest size you can send, add your PNGs, and each is cut to a palette of 256 colors, laid with dithering so gradients stay smooth, which makes most PNGs three to four times smaller. Only when that isn't enough is the picture drawn smaller. Transparency is kept throughout, and nothing is uploaded.

  1. Step 1

    Choose your PNGs
    Add one picture, several, or a folder.

  2. Step 2

    Set the size
    Type the largest size in KB, or pick one.

  3. Step 3

    Download
    Save each PNG, or all of them in a ZIP, once its size is checked.

What to expect

Supported inputs
PNG images, and any other picture: JPG, WebP, HEIC, AVIF, BMP, GIF, or SVG. Everything is saved as PNG.
What happens
A PNG under the size is kept as it is. Over it, the picture is saved with up to 256 colors chosen for it, with dithering, and its transparency kept. If that's still too large, the picture is drawn smaller, in steps, until it fits. Every file is read back and measured before you see it.
Limits
A photo saved as PNG stays far larger than the same photo as JPG; for a photo, Compress JPG gets much smaller files. Pictures with thousands of colors show a little grain from dithering when they're cut to 256. Very large pictures can be more than a phone's browser can hold.

Private by design

Your images stay on your device

Mastershot processes your file locally in this browser. It does not need to be uploaded to a server, and you do not need an account to use the tool.

  • No upload
  • No signup
  • No watermark

Questions

Yes. The palette keeps see-through and half-transparent pixels as they were.

A PNG stores every pixel exactly, so lowering quality the way a JPG does isn't possible. A palette of 256 colors is how a PNG gets much smaller while keeping its sharp edges, and for logos, screenshots, and drawings the difference is hard to see.

Only by making the picture smaller. Untick nothing and type a size the picture can reach at full color, or choose WebP under Save as, which keeps transparency at a much smaller size.

Yes. Add as many as you like, or a folder, and download them one by one or all together in a ZIP.

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