Stock Market · Trading Systems

Broker APIs for automation

Broker APIs (Application Programming Interfaces) let you execute trades programmatically. Your code places, modifies, and cancels orders without manual clicks. This is the foundation of all algorithmic trading.

Indian broker APIs

Most of the well-known Indian discount brokers now publish one. What varies:

• Cost: some bundle API access free with the account, others charge a monthly fee per app
• Rate limits, how many requests per second before you're throttled
• Whether historical data comes with it or is billed separately
• Whether a sandbox or paper-trading endpoint exists, which decides how safely you can test

What you can do with APIs

• Place market, limit, stop-loss, and bracket orders
• Modify or cancel existing orders
• Stream live tick data (with separate market data subscriptions)
• Pull historical data for backtesting
• Receive order/trade updates via websocket

A basic Python flow

1. Authenticate with API key + secret

2. Fetch live quote for stock

3. If condition matches your strategy (e.g., price > yesterday's high):

4. Place buy order via API

5. Set bracket order with stop and target

6. Monitor positions, adjust trailing stops

SEBI rules around algo trading

As of 2024-25, retail algo trading is in regulatory grey area:

• Strategies you build for personal use are generally OK
• Selling strategies to others requires SEBI approval (Research Analyst license)
• High-frequency strategies (>2 orders/second sustained) face additional scrutiny

Getting started

Most retail algos use Python. Resources:

• Your broker's own Python client library and API docs
• Open source backtesting libraries (Backtrader, vectorbt)
• Broker-published education portals, which usually document their own API in depth

> Don't deploy live until you've tested EXTENSIVELY in paper mode. Bugs in algo code can place hundreds of unwanted orders within seconds.

Takeaway. Broker APIs let you trade programmatically, and most Indian retail algos are written in Python. SEBI permits personal algo trading but restricts selling strategies to others. Code placing orders at machine speed turns a small bug into a large loss faster than you can react, which is what paper testing is for.