Apple has released new beta versions of iOS and macOS. These betas are specifically for developers, rather than public beta testers.
App writers can download and test beta 2 of iOS 10.2.1 and beta 2 of macOS Sierra 10.12.3. Apple has not said anything about this particular batch of betas, which likely resolve bugs and performance issues.
Apple typically makes the public betas for these platforms available a day or two after the developer beta.
