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Compress image

Compress pictures to a size in KB or MB, as many at once as you like, at the best quality that fits. 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.

A JPG, PNG, or WebP stays what it is. Other pictures become JPG, or PNG when they're transparent.

Transparent areas in a JPG

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

How to compress an image online

Type the largest size you can send, add one picture or a whole folder, and each is saved at the highest quality that fits under it, then drawn a little smaller only when quality alone can't get it there. The size is checked before you download. Everything happens in your browser, so your pictures are never uploaded.

  1. Step 1

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

  2. Step 2

    Set the size
    Type the largest size in KB, or pick one. Tick Not smaller than if a form sets one.

  3. Step 3

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

What to expect

Supported inputs
JPG, PNG, WebP, HEIC, AVIF, BMP, GIF, and SVG, one or many at once. HEIC opens in Chrome, Edge, and Safari on most computers, but not in Firefox.
What happens
A JPG, PNG, or WebP stays in its format unless you choose another; HEIC and other photos become JPG. JPG and WebP are saved at lower and lower quality until they fit, never below a quality that still looks like a photo, and only then is the picture drawn smaller. A PNG is cut to 256 colors with dithering before it's drawn smaller. Every file is read back and measured before you see it. If a form also sets a smallest size, tick Not smaller than and type it.
Limits
A picture already under the size is kept as it is. The smaller the size, the smaller a photo comes out. Very large pictures can be more than a phone's browser can hold; a computer handles them.

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

Type the size in KB under Largest size, or pick one of the usual ones, and add the picture. It's saved at the highest quality that fits, and the finished size is shown on its row.

Yes. Choose or drop as many as you like, or a folder. They're compressed one after another, and you can download them one by one or together in a ZIP.

A JPG, PNG, or WebP stays what it is unless you choose another under Save as. JPG gets a photo smallest; PNG keeps transparency and sharp edges; WebP is smaller than JPG for websites.

Tick Not smaller than and type the size. Quality goes up to reach it, and the picture is drawn larger if it has to be.

No. They're compressed in your browser, on your device, so nobody else sees them.

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