Does resizing happen on a server?

No — the image is redrawn on a canvas in your browser and never uploaded.

How does the aspect-ratio lock work?

With the lock on, changing width auto-updates height (and vice versa) to keep the original proportions.

Resize images to exact dimensions or by percentage, with optional aspect-ratio lock. Runs entirely in your browser — images never leave your device.

Runs in your browser — files never leave your device

Drop an image, or click to chooseResizes in your browser

Enter a target width or height. With aspect lock enabled, the other dimension is computed for you so the image isn’t distorted.

The output is a PNG to preserve quality; everything is processed locally.

Does resizing happen on a server?: No — the image is redrawn on a canvas in your browser and never uploaded.
How does the aspect-ratio lock work?: With the lock on, changing width auto-updates height (and vice versa) to keep the original proportions.