Perpetual Contract Unified Schema Design: Normalizing Binance, OKX, and Bybit Depth Snapshots

If you have ever tried to build a single trading dashboard that pulls order book data from Binance, OKX, and Bybit at the same time, you already know the pain: every exchange speaks its own JSON dialect. Symbols are spelled differently, prices arrive as strings instead of numbers, update IDs are called different things, and timestamps are wrapped in nested objects on some venues and flat on others. After a few hours of debugging KeyError and TypeError messages, most beginners give up and just pick one exchange.

This tutorial is written for absolute beginners. We will start from zero, look at the raw payload from each exchange side by side, then design a single unified schema, and finally write a small Python normalizer that converts all three into the same shape. By the end, your strategy code will not need to know which exchange the data came from, and you will be able to swap venues by editing a single config line.

Along the way I will show you how to plug this pipeline into the HolySheep Tardis-style crypto market data relay (Sign up here), which already delivers normalized trades, order book deltas, liquidations, and funding rates from Binance, OKX, Bybit, and Deribit through one WebSocket. That removes about 80 percent of the glue code you would otherwise have to maintain yourself.

Who this guide is for — and who it is not for

It is for you if:

You are a complete beginner who has never used a crypto exchange API before.
You can read basic Python (variables, dictionaries, for-loops).
You want one clean schema that works across Binance, OKX, and Bybit perpetual swaps (USDT-margined).
You care about reproducible research, backtesting, or running the same strategy across multiple venues.

It is NOT for you if:

You only trade on a single exchange and have no plan to expand.
You need coin-margined (inverse) contracts — this guide focuses on USDT-margined perps.
You need options Greeks on Deribit. (HolySheep supports it, but that is a separate tutorial.)

Step 1 — what a "depth snapshot" actually is

Think of an order book like a stadium. Each row has a price and a pile of people willing to buy or sell at that price. A "depth snapshot" is one photograph of the whole stadium at one millisecond. Most exchanges also send "delta" updates between snapshots — small diff messages that say "row 17 just got 12 more buyers." For this tutorial we focus on the snapshot; the deltas use the same unified schema once you normalize the snapshot.

A snapshot normally contains:

Exchange id — which venue sent it.
Symbol — for example BTCUSDT vs BTC-USDT-SWAP vs BTCUSDT (yes, OKX adds extra dashes).
Timestamp — when the snapshot was taken.
Bids — list of [price, size] pairs, highest price first.
Asks — list of [price, size] pairs, lowest price first.
Update id — a monotonically increasing sequence number used to reconcile deltas.

Step 2 — the raw payload from each exchange

Here is the exact JSON shape each exchange sends on its REST depth endpoint. Open these in any text editor side by side and you will see the differences immediately.

Binance — https://fapi.binance.com/fapi/v1/depth?symbol=BTCUSDT&limit=5

{
  "lastUpdateId": 1234567890123,
  "E": 1717000000000,
  "T": 1717000000999,
  "bids": [
    ["67890.10", "1.234"],
    ["67890.00", "2.500"],
    ["67889.90", "0.800"]
  ],
  "asks": [
    ["67890.20", "0.500"],
    ["67890.30", "1.000"],
    ["67890.40", "3.200"]
  ]
}

OKX — https://www.okx.com/api/v5/market/books?instId=BTC-USDT-SWAP&sz=5

{
  "code": "0",
  "msg": "",
  "data": [{
    "instId": "BTC-USDT-SWAP",
    "ts": "1717000000100",
    "bids": [
      ["67890.1", "1.234", "0", "4"],
      ["67890.0", "2.5",   "0", "8"]
    ],
    "asks": [
      ["67890.2", "0.5",   "0", "2"],
      ["67890.3", "1.0",   "0", "3"]
    ]
  }]
}

Bybit — https://api.bybit.com/v5/market/orderbook?category=linear&symbol=BTCUSDT&limit=5

{
  "retCode": 0,
  "retMsg": "OK",
  "result": {
    "s": "BTCUSDT",
    "ts": 1717000000200,
    "bids": [
      ["67890.10", "1.234"],
      ["67890.00", "2.500"]
    ],
    "asks": [
      ["67890.20", "0.500"],
      ["67890.30", "1.000"]
    ],
    "u": 987654321,
    "seq": 12345
  }
}

Notice four confusing things a beginner will hit immediately:

Symbol spelling: Binance and Bybit use BTCUSDT; OKX uses BTC-USDT-SWAP.
Timestamp units: Binance uses ERelated Resources 📚 AI API Tutorials 💰 View Pricing 📖 Developer Docs 🚀 Sign Up Free Related Articles duojiaoyisuozijinfeilvguiyihua5 dapingtaiyongxuhey tardis vs kaiko vs databento jiami l2 hangqingshuj jiamiqiquan greeks lishishujuderibit okx lianshang