A computer-implemented method, system and computer program product for protecting against application programming interface (API) attacks. A connection is established between an API user and an API provider. The established connection is then monitored to assess connection security and trustworthiness of the connection as well as trustworthiness of the API user and/or API provider. A score is then generated for each factor used in assessing the connection security and trustworthiness of the connection as well as the trustworthiness of the API user and/or API provider based on the monitoring. A level of risk for an API attack with respect to the API user and/or API provider is then generated based on such scores. An action (e.g., blocking traffic) is then performed with respect to the API user and/or API provider based on the level of risk for an API attack with respect to the API user and/or API provider, respectively.