<p>API trading refers to the practice of linking custom software—such as trading algorithms, analytical tools, or portfolio management systems—to a broker’s trading platform through an application programming interface (API). By using standardized requests and responses, traders can send orders, retrieve market data, and manage accounts programmatically, eliminating the need for manual entry via a graphical user interface.</p>

<h2>How It Works</h2>
<p>A broker exposes a set of API endpoints that follow common protocols such as REST, WebSocket, or FIX. Users authenticate with an API key or token, then issue HTTP or socket calls to perform actions like:</p>
<ul>
<li>Submitting market, limit, or stop orders</li>
<li>Cancelling or modifying existing orders</li>
<li>Fetching real‑time price quotes, historical candles, or order book depth</li>
<li>Checking account balances, margin requirements, and position details</li>
<li>Receiving event notifications (e.g., fill confirmations, price alerts)</li>
</ul>
<p>The custom application processes the returned data, applies its logic—whether based on technical indicators, statistical models, or risk rules—and sends the appropriate instructions back to the broker. Because the communication is automated, latency can be reduced to milliseconds, and operations can run continuously without human intervention.</p>

<h2>Why It Matters</h2>
<p>API trading enables traders to implement sophisticated strategies that would be impractical to execute manually, such as high‑frequency arbitrage, multi‑leg options spreads, or dynamic portfolio rebalancing. For example, a quantitative fund might use an API to monitor volatility across dozens of currency pairs; when a predefined spread widens, the system instantly sends opposing FX spot and forward orders to capture the spread while managing risk through pre‑set stop‑loss levels. This capability improves execution speed, reduces emotional bias, and allows scaling of strategies across multiple accounts or instruments. Moreover, API access fosters innovation by letting traders build proprietary tools, back‑test strategies with live data, and connect to third‑party analytics platforms, ultimately enhancing competitiveness in modern electronic markets.</p>