Abstract: Techniques for real-time delivery of personalized content are provided. An example method includes detecting that a delivery server invoked an API in response to the delivery server detecting that a client device is accessing a communication provided to the client device by the delivery server, the communication formatted in accordance with a template; receiving a request for offers, the request including a user identifier associated with a user of the client device and offer query criteria based on the template; building the offers by: retrieving candidate offers specific to the user from a database server using an API request; and, based on the offer query criteria, identifying the offers, from the candidate offers, to deliver to the delivery server; and transmitting the offers to the delivery server to cause the delivery server to populate the communication with content corresponding to the offers.