6. Cryptocurrency trading with Python: ccxt, the universal exchange translator

Level 3: Market Data and APIs

Every cryptocurrency exchange — Binance, Coinbase, Kraken — has its own API, with its own data format and its own rules. Writing different code for each one would be absurd if what you want is a strategy that works the same way on any of them. That is what ccxt (CryptoCurrency eXchange Trading) exists for, a Python library that offers a single interface to connect and trade on more than a hundred different exchanges without having to adapt your code to each one.

Its main advantages are several. A unified API: you learn one single way of requesting data or sending orders, and it works the same whatever the exchange, with minimal code changes when switching from one to another. Broad coverage: it supports the vast majority of relevant exchanges, from Binance and Coinbase to far smaller platforms. Standardized market data: tickers, order books, trade history, all in the same format, no matter which exchange it comes from. Real trading capability: it does not only read data, it also lets you place and cancel market and limit orders, and manage the ones you already have open. And it is open source and actively maintained, which in practice means that if an exchange changes its API, the library is usually updated quickly so things keep working.

To get started, all you need is to install it and initialize the connection with the exchange you want to use:

import ccxt

print(ccxt.exchanges)   # list of more than 100 supported exchanges

exchange = ccxt.binanceus({
    "enableRateLimit": True,  # stops the exchange from blocking you for too many requests
})

candles = exchange.fetch_ohlcv("BTC/USD", timeframe="1d", limit=100)

enableRateLimit is a detail you should never skip in real code: every exchange limits how many requests you can make per second, and exceeding that limit can end in a temporary — or permanent — block on your account. ccxt handles that waiting automatically when you enable this option, instead of you having to work it out yourself.

The order book is also directly accessible, and it is the most direct way to see, in real time, how many people want to buy and sell at each price level — the same concept you saw conceptually in Level 1, but now with real data in front of you:

depth = exchange.fetch_order_book("BTC/USDT")

bids = depth["bids"]   # resting buy orders
asks = depth["asks"]   # resting sell orders

As with any code that touches real money, two warnings are not optional: never share or upload your API keys to a public repository, and always test any strategy with a test account or with minimal amounts before risking real capital.