How can I open a new sandbox site for testing?

You'll want to first be logged out of any existing Recurly instances on your current browser. From there, please visit the page linked below and fill out all fields listed. Note that a new email address that is not associated with any other Recurly sites will need to be used in the registration process. An existing registered email cannot be used however, you will be able to invite any existing user's email address later as a site user once the site has been created.

https://info.recurly.com/signup

Once the signup has been completed, you'll want to visit your email that was used and accept the creation of the site. All that's left is to set your login password and head over to our login page to quickly gain access to your new site.

https://app.recurly.com/login

From there, you can invite any existing users that need access to the site by visiting the Users page under the Admin tab on the left-hand navigation menu. From the Users page, just click on Invite Users in the top right-hand corner of the page and you'll be all set to invite new users and set their user permissions. 

Additionally, you can add your primary email address as a user on your new site. This way when you login with your primary email address, there will be a dropdown menu at the top left-hand that will display all sites that are associated with that email to allow you to easily switch back and forth, as needed.