FlareSolverr is a proxy server to bypass Cloudflare protection.
I found it while looking for a way to fix a problem: my Jackett installation one day started to give errors when trying to access 1337x. You got the point...
Here are the instructions in order to get FlareSolverr configured and running at boot in a FreeBSD system or in a FreeNAS/TrueNAS jail (which is my case, by the way).
This works only for version 2.1.0. For version 2.2.0, I was unable to make it work. I'm sorry.