This is the final iteration of an R script I wrote years ago to manually calculate our league's Elo ratings. Now a fully fleshed out Python package, you can connect it to your fantasy league and calculate ratings based on completed matchups. If your league is a dynasty league you can get both the seasonal and all time ratings. You can adjust the K factor or off-season equilibrium rate to fit your league as needed.
What it supports
Platforms — Fantrax, Sleeper
Leagues — NBA, NFL
Formats — Categories, Points
If you have any feature requests, please feel free to email me here.