To save your API create an account
Mashape allows you to consume and monitor APIs in your Application, giving you a one stop shop for monitoring, payments, and management.
Invite developers to your public or private APIs. Mashape will send an email to them granting them access.
Rapleaf's Personlization API provides rich demographic data about email addresses in real-time.
You will need an Rapleaf API key in order to use this service. You can get one (for free) here: https://www.rapleaf.com/developers/api_access.