Image compressor
Reduce image size and compare the result.
JPEG turns transparent areas white. Keep originals if you need animation or photo metadata.
Reducing image file size
Select an image and adjust the quality. Compare the original with the result before downloading. Zoom in to check small text and thin lines.
Choosing a format
Compare JPEG and WebP for photographs. Avoid JPEG when you need transparency. An already compressed file may not shrink much and can become larger. Keep your original file.