Every Discord bot eventually gets the same feature request: "Can I customize the welcome message?" Seems simple enough. An admin wants to write something like: Welcome {user} to {server}! You're member #{count}. Enter fullscreen mode Exit fullscreen mode and your bot fills in the blanks. The first version I built looked exactly like you'd expect: const msg = template . replaceAll ( " {user} " , `<@ ${ member . id } >` ) . replaceAll ( " {server} " , guild . name ) . replaceAll ( " {count} " , String ( guild . memberCount )); Enter fullscreen mode Exit fullscreen mode Honestly, it felt done. Then reality showed up. A server owner wanted premium members to get a different welcome message. Another wanted to display the user's roles. Someone else wanted conditional content. Then eventually a user managed to get @everyone into a piece of user-generated content, and suddenly my bot was helping ping thousands of people.…