The final version of PHP 7 is available for download on Github and the PHP mirrors now. PHP7 is the next generation of the PHP programming language, it is up to 2 times faster than PHP 5.6 and 14 times faster than PHP 5.0 according to the release notes. The new PHP version is not 100% compatible with PHP 5.x as some deprecated API's have been removed, so it is a good idea to start testing your web sites for compatibility with this new release. This can be done easily and without affecting all sites on your server by using the multi PHP version feature in ISPConfig 3. https://www.howtoforge.com/tutorial/how-to-install-php-7-on-debian/
done. i setup a test site an call phpinfo(). it work under standard PHP 5.6.14-0+deb8u1 (debian 8, nginx) but if i switch via ispconfig to php7 it give me 502 bad gateway. (i manual restarted nginx & php5-fpm) have also 3 free bostrap (4) template that work without problem under php7.
@Nemis we sorted out some issues when mixing systemd AND initd I did a rewrite of this howto for debian 8 using only systemd here.