At the moment, OSRS has 4 J-mods, namely Mod Mat K, Mod Ash, Mod Nexus and Mod Reach. They are all employees who have worked for Jagex for quite a while now. They were (almost) all there when OSRS was the 'main game'. They make the development blogs for us, they organise polls, and much more!
Each J-mod of course also has his own speciality. Mod Ash and Mod Nexus are the content developers of OSRS. If we want to have new content for OSRS, they will be the ones making it! Mod Mat K is the community manager of OSRS. He organises events with the rest of the community, and he sometimes even hosts livestreams! Mod Reach is the technical one of the team, and he will make sure the game will be running. He also loves to destroy bots and fix bugs. What would we do without him?
Of course they are also very helpful. If you need help something, they will always try to solve it for you as soon as possible. Especially Mod Mat K and Mod Ash are very active on the forums, and are prepared to answer any questions. Mod Mat K even has his own Twitter and Twitch channel, where he gives hints about the locations of 'rares' and answers questions of players.
Anyway, I personally find them a great bunch of J-mods, and I'm very happy they are our Old School mods. They're always prepared to help us when needed, while they also like to joke around. They are also very social; they try to reply to every thread on the forums and to every question they get on twitter. I really hope that we will see more events with them soon, and I'm sure they will make OSRS even better than before!