Public betas are available to those who are enrolled in Apple’s free Beta Software Program. Once you’re signed up, and your devices are registered, you can access future iOS, macOS and tvOS betas using each platform’s over-the-air Update mechanism.
Help make the next releases of iOS, macOS, and tvOS our best yet. As a member of the Apple Beta Software Program, you can take part in shaping Apple software by test-driving pre-release versions and letting us know what you think.