Short answers for the converter on jpg-png.com. The tool itself is on the home page.
FAQ
Does PNG restore JPEG quality?
No. Detail already discarded by JPEG stays gone. PNG only stops further JPEG damage.
Why is the PNG bigger?
Lossless files keep more data. That is normal. Use WebP if you need a smaller web image.
Are photos uploaded?
No. A canvas encode in this tab.
Batch convert?
Up to 20 JPEGs. ZIP shows up after two or more are done.
Can I shrink the image?
Set Max width to 1920, 1280, 800 or 640. Original leaves the pixel size alone (capped at 8192).