Toss Securities launches open API service for conversational stock trading

Toss Securities announced Thursday the official launch of its open API service.

The open API service provides an application programming interface (API) that lets customers connect the brokerage's financial data and functions — including market prices, order execution and account information — to programs they build themselves or to external services.

Unlike some brokerages that have offered open APIs only to users with their own development environments, Toss Securities supports integration with large language models (LLMs), making the service accessible to users with no coding or development knowledge.

Toss Securities began accepting early applications in May and has been rolling out core API functions in stages. The official launch expands the service to all customers.

A key feature of the Toss Securities open API is its unified design: a single integrated API covers both domestic and overseas stock trading, allowing users to check market prices and place orders in both markets through one connection.

By linking an open API key to an external LLM such as ChatGPT or Claude, investors can place real orders, execute trades and retrieve account information without any coding knowledge. For example, a user can type a natural-language command such as "Buy 10 shares of Company A at market price," and the AI interprets the instruction and executes the actual order.

Functions available through the open API include stock information lookup, personal account information lookup, standard orders, conditional orders and real-time market prices.

"With the official launch of the open API, even ordinary investors without development or coding knowledge can now use AI to easily build their own investment strategies and apply them in practice," a Toss Securities official said. "Going forward, we will continue to support investors in building and running their own investment strategy systems in everyday life through the open API service."

Toss Securities has been rapidly expanding its customer base by rolling out an intuitive user interface and a range of AI-based services, including an "AI earnings call" feature. The number of cumulative account holders surpassed 10 million last month, while monthly active users reached 6.5 million.