Compress locally, not on a server
CollagePlus decodes and re-encodes images inside your browser. The Worker path keeps batch processing away from the interface thread, while Cancel stops the active queue and preserves completed results.
Target size behavior
The compressor first adjusts encoding quality. If a file still cannot meet the selected target, it may reduce pixel dimensions and clearly labels that result as resized.
Choose JPG or WebP
Auto keeps JPEG inputs as JPEG and turns PNG/WebP inputs into WebP. Choose JPG for broad compatibility; transparent pixels become white. Choose WebP for stronger compression and transparency support.
Already optimized images
If re-encoding cannot make a file smaller, it is not presented as a successful result. Lower the quality or choose WebP and try again.