An API gateway is a device or software that acts as an intermediary between clients and servers that provide web services through application programming interfaces (APIs). An API gateway can provide various functions such as:
Terminating SSL connections at a central location, reducing the overhead on the backend servers and simplifying certificate management Managing both authentication and authorization for incoming and outgoing web service calls, enforcing security policies and access control Advertising the web service API, providing documentation and discovery features for developers and consumers Implementing DLP and anti-malware features, preventing data leakage and malicious code injection