From Halopedia, the Halo wiki

A developer is an user that has access to certain database functions in order to manage the site. They also have the same abilities as an administrator and bureaucrat.

How do I become a developer?

While rarely given to another user, the developer user group is reserved for the owner of the domain and the person who hosts the site. Anyone else who holds this role is up to the discretion of the current developer.

Meet the developer!

If you need to contact the current developer, you can do so on their talk page or social board.