Apple’s Developer Center is where it keeps the documentation and resources third-party developers need to make their apps. If a registered developer needs to download the latest iOS or OS X build, they go to the Dev Center. It’s an invaluable resource Apple provides for $100 per year to each person in its developer program.
When the Dev Center goes down for maintenance, it usually only lasts for a few minutes. But for some unknown reason, the Dev Center has been down for well over 24 hours. Developers are scratching their heads on Twitter, and Apple hasn’t said anything.