(always out-of-date) Developer system status is visible here: https://developer.apple.com/system-status/
However this is mostly out of date and seems to be manually updated since hours go by at times and thousands of reports are needed (both via Feedback Reporter or the dev forums) before this page acknowledges an outage of any kind.
Please add a way to contact Apple directly from that page or "ping" whoever's concerned somehow so we can say "Hey guys, it's broken!". If enough people ping, then Apple can take some action. Right now iCloud / App Developer related services are offline multiple times a year and it's very inconvenient as no one even acknowledges till it's widespread everywhere (forums, stackoverflow, twitter etc).
Google Play Store services are super efficient in this regard - they respond to bug reports within a few hours, acknowledge it and are transparent. Their server outages seem to be automatically monitored and controlled so that human-operators can be pinged appropriately.
Every now and then the notarization service goes down and it's a pain because this means we can no longer notarize and push even "direct" macOS apps with critical fixes.
