Traditional organizations are increasingly becoming software producing organizations. This software is enabling them to integrate business processes between different departments and with other organizations through Application Programming Interfaces (APIs). The main task of managing APIs is to ensure that the APIs are easy to use by third parties, such as providing helpful documentation, monitoring API performance, and even monetizing API usage. The knowledge on API management is scattered across academic literature. In this document, we describe a Systematic Literature Review (SLR) that has the goal of collecting API Management practices and capabilities related to API Management, as well as proposing a comprehensive definition of the topic. In the scope of this work, a practice is defined as any practice that has the express goal to improve, encourage and manage the usage of APIs. Capabilities are defined as the ability to achieve a certain goal related to API Management, through the execution of two or more interrelated practices. We follow a standard method for SLRs in software engineering. We managed to collect 24 unique definitions for the topic, 114 practices and 39 capabilities.