To take advantage of TestFlight, simply upload a beta build of your app, and use App Store Connect to add the names and email addresses of people you’d like to test your app. Testers will install the TestFlight app for iOS, watchOS, and tvOS so they can use your beta apps and quickly provide feedback.
Each app can be tested by up to 25 members of your team who have been assigned the Admin, App Manager, Developer, or Marketer role in App Store Connect. Each member can test on up to 30 devices. Internal testers can access all of your beta builds available for testing.
Once you’re ready, you can invite up to 10,000 external testers who do not need to be part of your team to beta test an app that you intend for public release on the App Store. You can organize external testers into custom groups and share different builds with each group, depending on which features you want them to test. Before external testing can begin, the app must pass Beta App Review to make sure it complies with the full App Store Review Guidelines. Only the first build for the beta version requires a full review.
With TestFlight, developers simply upload a build, and the testers can install it directly from their device, over the air.