N-Body simulator

[repkon]

Where can I find software to check the stability of my planetary system?

[cubinator]

Try this: http://www.gravitation3d.com/

[UmbralRaptor]

Currently very frustrated that the main MERCURY6 website seems to have succumbed to bitrot. At least forks exist. (eg: https://github.com/4xxi/mercury)

[R-T-B]

If you are open to commercial options, I can heartily recommend Universe Sandbox as a decent n-body simulator that is very easily accessible:

http://universesandbox.com/

I sometimes use it to test Principia system models, with basically good results.

Edited November 29, 2020 by R-T-B