In general, we follow the requirements and recommendations by We recommend:

  • PHP version 7.4 or greater
  • MySQL version 5.6 or greater OR MariaDB version 10.0 or greater
  • HTTPS (SSL) support

Don’t have an SSL certificate? You can get one for as low as $10/year that meets all necessary security standards. We like Namecheap.

Some WordPress hosts offer Lets Encrypt free SSL built-in. See this guide on free SSL from WP Beginner.

Updated Dec. 3, 2016.

Additional PHP and WP Version Support

At a bare minimum, the included Google API PHP library and our plugin structure require PHP 5.5 (version 3.1.10 and lower require 5.3) even in legacy environments. PHP 7 or higher is still strongly recommended for security reasons.

The following PHP extensions are also required. Most web hosts should have them enabled by default.

curlread more
iconvread more
jsonread more
mbstringread more

If you are running into PHP memory issues see: Troubleshooting Memory Errors

We highly recommend that you keep your version of WordPress current, but we generally support a couple versions back as long as the latest security patches have been applied.

System Report

To view your server specifications, head to Calendars > Tools > System Report in your WordPress admin.

Feel free to reference this page if you need to request an update from your web host.

See also Troubleshooting Theme, Plugin and Widget Conflicts.