Apple's TestFlight service is currently down for many, following an earlier iTunes Connect outage.
TestFlight is Apple's beta testing service, which allows developers to test their apps in pools of 1,000 users. Following a service disruption in the iTunes Connect developer portal, TestFlight has been experiencing an outage for some all morning. It is currently affecting developers in the U.S. and Canada, while developers in other locations are probably impacted as well.
The disruption prevents testers from downloading apps from the service, and developers cannot send out new versions. Many report receiving a "currently unavailable" message when they try to install apps in TestFlight. Apple has yet to update their Developer System Status page to acknowledge the outage.