A treasury API is a bank API, or a set of them, aimed at corporate treasury work. It lets a company's software retrieve account balances and transactions in real time, initiate payments, check their status, move funds between accounts and, with some providers, book foreign exchange or place surplus cash. The company connects its treasury management system or accounting platform to the interface instead of logging in to a banking portal.
The main benefit over the older file-based host-to-host connection is immediacy. Balances can be checked on demand, which improves cash visibility and cash positioning, and payments over instant rails can be sent and confirmed at any hour. The term is also used by banking-as-a-service providers for interfaces that let software platforms hold funds for their business customers and move money on their behalf. Because each bank's interface differs, companies with many banks often use an aggregator that presents them through one connection.