Read the order book. Preserve the signal.

One venue, one product, one interpretation

A BTC-USD book and a BTC-USDT book are not the same dataset. Preserve the venue, product identifier, base asset, and quote asset with every observation. Top-of-book prices, price-level depth, and order-level records answer different questions. Choose the level of detail your application actually needs rather than collecting a complex stream without a clear purpose.

Use documented book semantics

Coinbase Exchange documents market-data and trading interfaces separately. Its official introduction identifies public market-data access and authenticated trading operations. For book reconstruction, follow the exact channel protocol. Do not assume an update is a quantity delta: some messages report a replacement size at a price level. The order-book article explains a small fixture that catches this mistake.

Give synchronization a first-class state

Track initializing, synchronized, recovering, and unavailable states in your application. An open socket does not prove that a valid initial book has arrived. On a continuity problem, stop presenting the local book as current and rebuild using the provider’s documented procedure. A polished chart should not conceal a gap behind an animated connection badge.

Keep numeric and execution boundaries clear

Use decimal-safe representations for prices and quantities and document how the interface aggregates levels. A hypothetical fill estimate is a scenario using observed depth, not a guarantee that the same liquidity will remain available. Keep account order records separate from the public book: aggregate changes do not establish whether a particular customer’s order filled.

Before you ship

Test zero-size removals, reconnects, invalid payloads, precision limits, and slow consumers. Keep credentials for trading operations outside browser code and separate from read-only data access. Record the source timestamp and receipt timestamp, then define which one your freshness indicator uses. Start with one verified adapter before expanding to additional exchanges.