How to put existing simulation tooling on the web?

I have once developed a tiny simulation tool that, given certain parameters, simulates a number of days of business so that one can gain insight into the performance of the business. I have done this in Java.

Now I would like to launch the same tool on the web, preferably with as little work as possible - as I already have working code for the matter. However, I am searching for the right approach to do so. The idea is that instead of inserting the parameters in a GUI, the user now needs to feed them to the tool through a form (or something like that). The tool then runs on the backend, and gives the results back to the user on the web page.

The thing is that it should be fast - I don't want to have users wait a minute before they get their results. My current tool simulates 100,000 days in about 3 seconds.

Basically, the question is: is it possible to run the existing Java code on the backend? If so, what would be the way to do it? If not, what would then be a good way to face this problem? (Learning other programming languages is not an issue, so if necessary that will be covered.)

Thanks in advance for thinking along with me!