XnView Software

what is a good conversion tool from JPG to WebP? Where you can still make settings?
I use XnView Classic XnView v2.51.5

If I save a JPG with 594 kB as WebP with XnView, it becomes 3.43 MB. What is XnView doing wrong?

If I use an online tool, a 594 kB JPG becomes a 432 kB WebP. However, I cannot make any settings online.

you can change the webp quality in settings

Experiment with compression settings such as quality, target size, etc. in XnConvert or other specialized software to attain a balance between file size and image quality. Different settings might yield better results and for image compression jpeg compressor and there are a lot of compression application available in internet which compress images, supporting various kind of images and they convert too.

That's what I use. I create JPG graphics in Gimp and then convert them to webp in Xnview - with 80% settings

It preserves much lighter files with almost the same quality.