Compress PNG
Shrinks PNG files with a palette of 256 or 128 colors, or losslessly. oxipng then optimizes the compression; transparency is kept either way.
This browser does not support background processing. Please use a current version of Chrome, Edge, Firefox or Safari.
Drop images or folders here
or
Images are processed in your browser and never uploaded. Metadata (including GPS) is removed unless you choose “Keep metadata”.
Your browser sends Global Privacy Control, so no numbers are shared.
Many files: processing runs in your browser, and how long it takes depends on your device.
From the Solo plan
Measure whether smaller images improve LCP
Once the images are replaced, daily measurement in a plan shows the effect: lab and field data per URL over time, with an email on drops and optionally on improvements.
Palette PNG for graphics, WebP for photos
Logos, icons and screenshots with few colors get much smaller with a color palette and no visible difference. Photos saved as PNG, on the other hand, are almost always too large; WebP or AVIF with transparency is the better choice for them.
Images for websites: sizes, formats and srcset
An image should only be as wide as it is displayed. The responsive series creates widths from 480 to 1,920 pixels, and the browser picks the right one through srcset and sizes. The picture element lists AVIF first, then WebP, with JPG or PNG in the img element as the fallback.
width and height on the img element reserve the space before the image loads and so prevent layout shifts (CLS). For the largest image in the visible area, usually the LCP element, the "LCP image" option sets fetchpriority="high" and leaves out loading="lazy".
Processing in your browser
All images are processed on your device, nothing is uploaded. Metadata such as camera data and GPS coordinates is removed unless you choose “Keep metadata”, and the orientation is applied to the pixels first. The limit is your device's memory and processor; images over 50 megapixels are skipped.
After a run the compressor can send anonymous numbers: format, size, pixel dimensions, savings and duration, never file names or images. The switch below the drop zone turns this off; with Global Privacy Control active it is off from the start.
Other formats
FAQ
What does a 256-color palette mean?
The image is reduced to at most 256 colors and each color is stored once. Graphics barely change, photos with gradients can show banding.
Is lossless PNG compression really lossless?
Yes. oxipng only changes how the data is stored, every pixel stays the same. The saving is smaller than with a palette.
Is transparency kept?
Yes, with palette and lossless. Only when converting to JPEG does the transparent area turn white.
Are my images uploaded?
No. Processing runs entirely in your browser. At most anonymous numbers (format, size, savings) go to PerfDelta, and you can turn that off.
How many images can I compress at once?
There is no fixed limit. Your device's memory and processor set the limit.
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- Core Web Vitals Test: Checks LCP, INP and CLS of real visitors against Google's thresholds and shows which pages fail and why.
- Mobile Website Speed Test: Measures how fast a site loads on phones, with real-user data from mobile Chrome and a throttled lab test.
- TTFB Test: Shows how long real visitors wait for the first byte of a URL and of the whole origin, from Chrome UX Report data.
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Third-party licenses
Encoding uses jSquash (Apache-2.0) with mozjpeg, libwebp, libavif, libjxl and oxipng, plus UPNG.js and fflate (MIT). Full license texts: THIRD_PARTY_LICENSES.txt
A free account saves your tests and shows how your values change from one test to the next. Daily monitoring with field data and alerts starts with the Solo plan.