As announced on the PHP.net site today the first Release Candidate for the PHP 7.1.x series has been released: PHP 7.1.0 RC 1.
The PHP development team announces the immediate availability of PHP 7.1.0 Release Candidate 1. This release is the first release candidate for 7.1.0. All users of PHP are encouraged to test this version carefully, and report any bugs and incompatibilities in the bug tracking system.
[...] For more information on the new features and other changes, you can read the NEWS file, or the UPGRADING file for a complete list of upgrading notes. These files can also be found in the release archive.