https://croppy.beta1042.duckdns.org/
My husband made this for you guys
You can feed it PNG, PSD, TIFF, or JPG files
For LINE Webtoon- it resizes your images to 800 width and cuts it 1280 heights and gives you JPG files.
For Tapas- it resizes files larger than 940width is resizes to 940 width and cuts heights of 700 and gives you PNG files. (they're so short because it guarantees your files are below the 2mb limit)
It's alittle slow, and slows the more people are using it at the same time.
If you see any issues let me know and he can work on debugging.