Resize an image
Change the width and height of any image without uploading it anywhere.
What to know
Resizing happens through the browser's own image scaler, the same one used to display any picture on a web page. Reducing dimensions is essentially lossless in perceptual terms; enlarging cannot invent detail that was never captured, so an upscaled image always looks softer than a native one.
Keep proportions is on by default. Turning it off lets you set width and height independently, which will stretch the image — occasionally what you want, usually not.
Questions
Is anything uploaded to a server?
No. Every tool on this site runs inside your browser using standard web APIs. There is no upload, no account, no logging and no server holding your data afterwards. You can confirm it by opening your browser's developer tools and watching the network tab stay empty while you work.
Will resizing reduce the file size?
Almost always, and substantially — halving both dimensions removes three quarters of the pixels. If you need a smaller file at the same dimensions, compress it instead.