Api trading
Family V · Platforms
Not to be confused with fix api.
API trading replaces or supplements a trading terminal with programmatic access to a venue's order and data services. The interface is defined by the venue or broker, and access is normally granted only after an application, key issuance and, in many jurisdictions, a suitability or permission check. Because each provider specifies its own endpoints, authentication and rate limits, API trading is not a single standard but a family of provider-specific interfaces.
How API trading works
An API trading connection typically involves three components: authentication credentials, a request format and a response format. Credentials may be an API key and secret, an OAuth token or a session identifier, depending on the provider. Requests are usually sent over HTTPS as REST calls, over a persistent WebSocket for streaming data, or through a binary protocol.
Common operations include:
- Submitting, amending and cancelling orders.
- Querying balances, positions and order history.
- Subscribing to quotes, trades and account updates.
Providers publish their own rate limits, symbol conventions and error codes. Exceeding a rate limit can result in throttling or a temporary ban, so automated strategies usually implement request queues and backoff logic.
Worked example: order placement and fill
An automated strategy sends a market buy for 500 shares of a stock quoted at 25.10 / 25.12. The API returns an acknowledgement, then a fill confirmation.
Operational and regulatory considerations
API access is not universal. Some brokers restrict it to professional or institutional clients, some charge a monthly fee, and some offer it only on certain account types. Regulatory treatment also varies: in some jurisdictions an automated strategy may require registration or pre-approval, while in others it falls under existing conduct rules. Because these conditions differ by provider and country, the specific terms must be read from the venue's API documentation and client agreement rather than assumed.
Technical risks include stale data, partial fills, duplicate order submission after a timeout and credential compromise. A common safeguard is an idempotency key or client order ID so that a retried request is not executed twice.
Often confused with
- fix api
- The FIX API is a specific implementation of API trading that uses the Financial Information eXchange protocol, a standardised message format with session-level sequencing and heartbeats, whereas API trading is the broader category that also includes REST, WebSocket and proprietary interfaces; the visible sign is whether the documentation specifies FIX message types such as NewOrderSingle or a REST endpoint such as POST /orders.