Choose the limit your destination actually requires.
A form that accepts images up to 100 KB needs a file at or below that limit, not simply a file marked high compression. This tool reports the real encoded output size. Its KB setting uses 1,024 bytes per KB; if a portal defines its limit in decimal bytes, choose a slightly lower target and verify the final upload. A successful compression does not confirm that the destination accepts the chosen format or dimensions.
Compression quality and dimensions solve different problems.
JPEG and WebP reduce file size by discarding some detail. If lowering quality cannot reach your limit, enabling dimension reduction also decreases the number of pixels. That can help with photographs but may make small writing illegible. The output dimensions are shown beside the actual size. If a registration form requires both exact dimensions and a small file size, resize first and then compress with dimension reduction disabled.
Check transparency and fine details before downloading.
JPEG does not support transparent pixels, so transparent areas are placed on white. Choose WebP if transparency matters and the destination supports it. This tool removes most original metadata by drawing a fresh image, but it is not a forensic metadata removal service. Zoom into faces, signatures and text in the downloaded file before using it for an application.
Process batches without mixing up the results.
Each file is processed separately and gets its own success or error state. You can download a finished image even when another file fails. Batch ZIP filenames include a numbered prefix to prevent two identically named input files from overwriting one another. Very large photos and complex HEIC files may take longer on phones; cancel processing or choose a smaller batch if the device becomes unresponsive.