Northstar is a modding framework/launcher: https://github.com/R2Northstar

Yup, Northstar lets you self-host multiplayer servers for Titanfall 2, with non-standard game modes, settings, and map rotations. And with the Northstar client (modded TF|2 app) you can access a server browser for Northstar servers, so you don't need to go through the official servers at all.

Northstar first got really popular in a period when the official Titanfall 2 servers were extremely unreliable - you'd either be stuck matchmaking forever even with a supposedly large number of players online, or you'd start a game with 12 players and be lucky to have 3 or 4 of them still connected by the end. Most people blamed the problems on DDoS attackers, and although the game developer Respawn acknowledged the problems, they never really delivered a server-side or client-side fix for them. So, the only enjoyable way to play TF|2 on PC was with Northstar.