Resize or crop by rectangle, square, circle, or freehand eraser. All in-browser.
Image Resizer lets you resize and crop images in your browser using three modes: exact pixel dimensions (with preset sizes like 1920×1080 or 512×512), percentage scaling, or target file size optimization that automatically finds the best quality and dimension combination. You can also apply crop regions in rectangle, square, circle, or rounded-corner app-icon shapes, and use a freehand eraser to paint transparency into any area of the image.
Output can be exported as PNG, JPEG, or WebP. The entire resize and crop pipeline runs on an HTML5 Canvas in your browser — your images are never uploaded to a server, ensuring complete privacy for screenshots, mockups, and personal photos.
The circle and app-icon (rounded rectangle) crops use the Canvas 2D compositing API. The image is drawn to an offscreen canvas, then a clipping shape is applied using destination-in compositing — pixels outside the shape become fully transparent. The result is saved as a PNG or WebP to preserve the transparency channel. Exporting a circle crop as JPEG will flatten the transparency to a white or black background.
Target Size mode uses a binary search algorithm to find the highest JPEG/WebP quality setting that keeps the output file below your specified size in KB or MB. It runs up to 12 iterations on the original dimensions, and if that is not enough to hit the target, it also scales down the image dimensions proportionally. The final quality percentage and achieved file size are displayed in the result bar.
In Pixels mode, you enter width and height independently — the tool does not lock the aspect ratio automatically, giving you full control for stretching or squashing. In Percentage mode, both dimensions scale proportionally from the original size. In the crop panel, enabling the "Lock" checkbox constrains the crop selection to the original image's aspect ratio.