Open API

An Open API is like a company opening a single door into a specific function of its service, letting other programs or developers come through that door and use the function directly. Instead of welcoming guests through the main entrance, it's like setting up a separate delivery window so that instead of a person, a courier or an automated system can drop things off directly.

Take a brokerage as an example. Normally, a person taps the app screen with their finger to place an order. Once an Open API is opened, a program can go through that gateway and place orders in place of a person. Domestic Korean brokerages typically verify identity using two keys, called an app key and a secret key, then exchange data in a fixed format—this means any program, whether built on a Mac, Linux, or any other computer, can connect.

Recently, it has become more common for AI agents to write the code themselves, rather than humans writing it, and have that code knock on the Open API. Unlike U.S. brokerages, which opened the door directly to agents using a standard connection protocol, in Korea there's an extra step: the agent writes code, and that code then calls the Open API.

One article states, "If Meritz Securities rolls out an Open API within the year, the 100 trillion won mark comes into view." A common misunderstanding is that an Open API is a door anyone can walk through without any restriction, but in reality it's an official gateway usable only by developers or programs that have gone through an authentication process such as an app key and secret key.