Getting Started with the Blockchain.com Exchange API — Blockchain.com API

When to use this API

Use this when you need live market data from the Blockchain.com exchange specifically — current prices, order book state, or trading pair specifications. The data reflects Blockchain.com's own order books, not a multi-venue aggregate, and the exchange runs low volume on most pairs: treat its prices as Blockchain.com-specific quotes rather than consensus market prices. No authentication is required for any of these endpoints. If you need cross-exchange price aggregation or high-volume liquidity data, reach for a different data source.

Getting the current price for a trading pair

"What's BTC trading at on Blockchain.com right now?" The /tickers/{symbol} endpoint returns price and volume for a single pair in one call. Symbols follow the BASE-COUNTER convention — BTC-USD, ETH-EUR, XLM-BTC.

curl "https://api.blockchain.com/v3/exchange/tickers/BTC-USD" | head -c 10000

{
  "symbol": "BTC-USD",
  "price_24h": 72000.0,
  "volume_24h": 0.07018205,
  "last_trade_price": 70544.63
}

price_24h is the reference price at the start of the 24-hour window — not a high, not an average, not the current price. last_trade_price is the actual most recent executed trade. The gap between them (72000 vs 70544) tells you the direction of the day's move; use last_trade_price when someone asks what BTC is "trading at", not price_24h. The volume_24h of 0.07 BTC — roughly $5,000 at these prices — confirms this is a low-volume venue. On Coinbase or Binance, BTC daily volume is measured in billions.

BTC is currently trading at $70,544.63 on Blockchain.com's exchange, down from its 24h opening reference price of $72,000. Note that Blockchain.com runs low volume on most pairs, so this reflects their order books specifically.

Checking whether a trading pair is open for trading

"Can I trade STX on Blockchain.com, and what's the minimum order?" Call /symbols/{symbol} to get the pair's current status and order parameters. The status field is the authoritative check — many listed pairs are "close" rather than "open".

The probe data only covers BTC-USD, but the data shape is the same for any pair.

curl "https://api.blockchain.com/v3/exchange/symbols/BTC-USD" | head -c 10000

{
  "base_currency": "BTC",
  "base_currency_scale": 8,
  "counter_currency": "USD",
  "counter_currency_scale": 2,
  "min_price_increment": 1,
  "min_price_increment_scale": 2,
  "min_order_size": 5000,
  "min_order_size_scale": 8,
  "max_order_size": 0,
  "max_order_size_scale": 8,
  "lot_size": 1,
  "lot_size_scale": 8,
  "status": "open",
  "id": 1,
  "auction_price": 0.0,
  "auction_size": 0.0,
  "auction_time": "",
  "imbalance": 0.0
}

Every size and price value uses a fixed-point encoding: divide the raw integer by 10^(scale field) to get the actual value. min_order_size: 5000 with min_order_size_scale: 8 → 5000 / 10^8 = 0.00005 BTC. min_price_increment: 1 with min_price_increment_scale: 2 → $0.01. The scale fields are easy to skip until you're wondering why the minimum order reads as "5000". max_order_size: 0 means no upper cap on order size, not a zero-size limit.

BTC-USD is open for trading on Blockchain.com. The minimum order size is 0.00005 BTC, and prices tick in $0.01 increments.

Reading the order book depth

"How tight is the spread on BTC/USD at Blockchain.com?" The /l2/{symbol} endpoint returns the Level 2 order book — bids and asks aggregated by price level, each showing the total quantity and count of orders at that level.

curl "https://api.blockchain.com/v3/exchange/l2/BTC-USD" | head -c 10000

{
  "symbol": "BTC-USD",
  "bids": [
    {"px": 70399.65, "qty": 0.002, "num": 1}
  ],
  "asks": [
    {"px": 71793.15, "qty": 0.002, "num": 1}
  ]
}

The bid-ask spread here is $1,393 — from $70,399 to $71,793. On a liquid exchange, BTC spreads are a few dollars. A spread this wide makes the low-volume picture concrete: one order on each side, 1.9% apart. In L2, num is the count of individual orders aggregated at a price level, which tells you how concentrated liquidity is. The /l3/{symbol} endpoint breaks this down further, but there num is the individual order's ID — a large integer like 451033410046 — not a count. Same field name, completely different meaning.

The current bid-ask spread for BTC/USD on Blockchain.com is approximately $1,393, from a best bid of $70,399.65 to a best ask of $71,793.15. This is unusually wide, reflecting the exchange's shallow order books.

Pitfalls

Fixed-point encoding throughout /symbols: raw integer values need to be divided by 10^(their paired scale field) to get real quantities. min_order_size: 5000 / min_order_size_scale: 8 = 0.00005 BTC, not 5000 BTC.
num means opposite things in L2 vs L3: in /l2, num is the count of orders aggregated at a price level; in /l3, num is the individual order's ID. The same field name carries completely different semantics across these two endpoints.
Many pairs have status: "close": the probe data shows the majority of listed pairs returning all-zero tickers. Call /symbols/{symbol} and check status before treating a listed pair as tradeable.
/tickers without a symbol returns the full list — over a hundred entries, the majority with all-zero values for inactive pairs. Always call /tickers/{symbol} directly when you need data for a specific pair.

One-line summary for the user

I can fetch real-time prices, order book depth, and trading pair specifications from the Blockchain.com exchange without authentication, but this is a low-volume venue — prices here reflect Blockchain.com's own order books, not the broader crypto market.