Do users need to leave an email address in order to create a demo?

No. Just need to enter the result of a simple math captcha.
The paid plans may allow you to ask for an email before creating the demo.

Are there any server requirements?

You don’t need to worry about that because we are the ones hosting the demo sites.

What are the server’s specs?

We have multiple demo servers in different locations. We ensure that the servers have enough resources to work and upgrade them as necessary.
The configurations usually are:

  • 4-32GB RAM
  • SSD storage
  • OS: Linux
  • PHP: 7.4
  • Database: MariaDB
  • max_input_time = 90
  • max_execution_time = 60
  • memory_limit = 256MB
  • exec(), system(), shell_exec() functions are not available for security reasons

I want to whitelist the demos in my license management server

Great idea. By the way you can enter your license key in the demo site template and have the license key removed later on from each demo site.
Do whitelist demo sites that match this: *.wpdemo.org/*

How to update the demo site template?

When you create a full demo site template you’ll be provided with a private WordPress site that you can customize. You can either update everything by logging into that WordPress site or from within the demo site settings by clicking a single update button.

How the sites domain looks like?

We set up demo sites on subdomains that end in wpdemo.org
For example us1.wpdemo.org, us2.wpdemo.org, eu1.wpdemo.org, eu2.wpdemo.org