Riverchat (also known as Chillchat, Together, and Mr. Rivers' Neighborhood) is an online chat room application created by Rivers Cuomo, as a project for an online web programming class (Harvard's CS50W course, via the online course provider edX), and hosted on his personal website, beginning in July of 2020. Cuomo has used the application to communicate with fans, sometimes in the form of cryptic non-sequiturs, and sometimes sharing previously-unknown Weezer-related trivia. It is speculated, though unconfirmed, that Cuomo has integrated a bot account to occasionally post replies on his behalf. The site was renamed "Chillchat" from "Riverchat" in late August of 2020.
Chillchat is comprised of different sections with the main, and only permanent, one being "#general", but having other sections such as "#spectacularly" and "#2020-AD". Users need an account to register and interact with other users, as well as write and receive messages, but they are allowed to read messages without one.
Besides being able to chat, Chillchat also provides users with links to different social media accounts owned by Rivers, such as his Twitter account, Facebook page, Instagram profile, Snapchat and personal Spotify.