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.
With an API key, you will have free, unlimited access to age, gender, and city/state/country data.
Additionally, we provide many other premium fields for a small price. Please visit our website or email us at firstname.lastname@example.org to get more info on pricing and our premium fields.