Yes it is lighter than the Electron-based options. Definitely a lot more than Postman which always consumes north of half a gig. Everest hovers around 250-300MB which I know is still a lot and I'm currently in the process of optimizing the internals.
And another yes, Java is not the lightest thing around. But man its much better than Electron.
Maybe I'm a spoilt C++ programmer, but 250-300 MB is still bit higher for my tastes. For me the golden standard of cross-platform desktop app is Sublime Text which usually hovers around 100-150 MB for me.
However I'm sure the memory usage, and performance can be drastically improved given the fact that JVM is one of the most heavily optimised pieces of software in recent times.
Edit: I just tried it, and it doesn't work for some of the methods for httpbin. Would be great if you could test the app against https://httpbin.org
I understand that 250-300MB is still a bit heavy, I'm not too happy with it either, but I've come to realize that even a Hello World JavaFX application with just a button on screen eats 70MB. I'm trying my level best to keep this at 200MB but I can't make any promises.
I sometimes wish I'd done this with C++, but it would be very tedious. I was quite proficient in JavaFX so I reckoned it will be the best tool for the job.
About httpbin: Could you please elaborate on that? Which method failed?
Don't get me wrong, 250-300 MB is perfectly fine. As long as it doesn't grow exponentially and take over the system like Electron apps do, people would love to use this. I think you've got a solid product at hand and you should try to grow this commercially.
And another yes, Java is not the lightest thing around. But man its much better than Electron.