API Specification

1. Overview

The Microverse Systems WebSocket API provides real-time, normalized L2 order book data from 21 cryptocurrency exchanges through a single JSON-over-WebSocket endpoint. Data is captured at the network layer with nanosecond-precision timestamps, normalized into a canonical format, and distributed with sub-millisecond latency.

Key Features

21 exchanges — Binance, Coinbase, OKX, Bybit, Kraken, Gemini, Crypto.com, Gate.io, KuCoin, Upbit, Bitget, MEXC, HTX, Bitfinex, BingX, Phemex, LBank, BitMart, CoinEx, AscendEX, Deribit
4 channel types — BBO top-of-book, consolidated aggregated books, full cross-exchange books with attribution, single-exchange books
1000+ symbols — Full depth (up to 100 levels per side)
Sub-millisecond delivery — C++ pipeline with zero-copy shared memory transport
Nanosecond timestamps — Hardware-timestamped at the NIC where available

2. Connection

Endpoint

wss://api.microversesystems.com

Protocol

Parameter	Value
Transport	WebSocket (RFC 6455) over TLS 1.3
Frame type	Text frames (opcode 0x1)
Encoding	UTF-8 JSON
Keepalive	Client should send `ping` every 30s
Max message size	1 MB

Quick Start

const ws = new WebSocket("wss://api.microversesystems.com");
ws.onopen = () => ws.send('{"op":"subscribe","channel":"fullbook:BTC-USDT","depth":20}');
ws.onmessage = (e) => console.log(JSON.parse(e.data));

3. Authentication

The public API does not require authentication. Connect directly and subscribe to any channel. Rate limiting is applied per IP address.

4. Message Format

All messages are JSON objects sent as WebSocket text frames.

Client → Server

Every client message must include an op field specifying the operation.

{
  "op": "subscribe",
  "channel": "fullbook:BTC-USDT",
  "depth": 20
}

Server → Client

Every server message includes a type field identifying the message type.

{
  "type": "snapshot",
  "channel": "fullbook:BTC-USDT",
  "data": { ... }
}

5. Client Messages

Subscribe to a market data channel. The server responds with a subscribed acknowledgment followed by continuous snapshot updates.

{
  "op": "subscribe",
  "channel": "fullbook:BTC-USDT",
  "depth": 20
}

Field	Type	Required	Description
op	string	required	`"subscribe"`
channel	string	required	Channel to subscribe to. See Channel Types.
depth	integer	optional	Max price levels per side (1–100). Default: 20. Ignored for `top:` (always 1).

Channel format

# BBO — best bid/offer, 1 level, aggregated across exchanges
"channel": "top:BTC-USDT"

# Consolidated book — aggregated multi-level, no exchange attribution
"channel": "consbook:ETH-USDT"

# Full book — all exchanges with attribution
"channel": "fullbook:BTC-USDT"

# Single exchange book
"channel": "binance:BTC-USDT"

5.2 unsubscribe

Unsubscribe from a previously subscribed channel.

{
  "op": "unsubscribe",
  "channel": "fullbook:BTC-USDT"
}

Field	Type	Required	Description
op	string	required	`"unsubscribe"`
channel	string	required	Channel to unsubscribe from.

5.3 ping

Application-level keepalive. Send every 30 seconds to maintain the connection.

{ "op": "ping" }

Server responds with:

{ "type": "pong" }

5.4 exchanges

Request the list of connected exchanges with live status and symbol counts.

{ "op": "exchanges" }

5.5 symbols

Request available symbols. Optionally filter by quote currency or exchange.

{
  "op": "symbols",
  "quote": "USDT",
  "exchange": "binance"
}

Field	Type	Required	Description
op	string	required	`"symbols"`
quote	string	optional	Filter by quote currency (e.g. `"USDT"`, `"USD"`).
exchange	string	optional	Filter by exchange ID (e.g. `"binance"`).

6. Server Messages

6.1 snapshot

Book data pushed after subscribe and on each update. The level array format varies by channel type.

Full book (`fullbook:`) — with exchange attribution

{
  "type": "snapshot",
  "channel": "fullbook:BTC-USDT",
  "data": {
    "bids": [
      [83450.50, 1.234, 5, "binance"],
      [83450.25, 0.891, 3, "coinbase"],
      [83449.80, 2.100, 8, "okx"]
    ],
    "asks": [
      [83451.00, 0.750, 2, "binance"],
      [83451.25, 1.500, 4, "bybit"]
    ],
    "ts": 1712200000000
  }
}

BBO (`top:`), consolidated (`consbook:`), and single exchange — no attribution

{
  "type": "snapshot",
  "channel": "binance:BTC-USDT",
  "data": {
    "bids": [
      [83450.50, 1.234, 5],
      [83450.25, 0.891, 3]
    ],
    "asks": [
      [83451.00, 0.750, 2],
      [83451.50, 1.100, 1]
    ],
    "ts": 1712200000000
  }
}

Level array fields

Index	Field	Type	Description
0	price	float	Price level. Adaptive decimals: 2 (≥1000), 3 (≥10), 4 (≥1), 6 (≥0.01), 8 (<0.01).
1	qty	float	Total quantity at this price level. Up to 8 significant figures.
2	orders	integer	Number of orders at this price level.
3	exchange_id	string	Exchange ID. Only present in `fullbook:` channel.

Ordering: Bids are sorted descending by price (best bid first). Asks are sorted ascending by price (best ask first).

Timestamp

Field	Type	Description
ts	integer	Milliseconds since Unix epoch (UTC). Server-side timestamp of the snapshot generation.

6.2 subscribed / unsubscribed

Acknowledgment messages confirming subscription changes.

{ "type": "subscribed", "channel": "fullbook:BTC-USDT" }
{ "type": "unsubscribed", "channel": "fullbook:BTC-USDT" }

6.3 exchanges response

{
  "type": "exchanges",
  "data": [
    {
      "id": "binance",
      "name": "Binance",
      "quote": "USDT",
      "symbols": 145,
      "status": "live"
    },
    ...
  ]
}

Field	Type	Description
id	string	Exchange identifier used in channel names.
name	string	Human-readable exchange name.
quote	string	Primary quote currency for this exchange.
symbols	integer	Number of live symbols on this exchange.
status	string	`live`, `stale`, or `pending`.

6.4 symbols response

{
  "type": "symbols",
  "data": [
    {
      "symbol": "BTC-USDT",
      "exchanges": ["binance", "coinbase", "okx", "bybit"]
    },
    ...
  ]
}

Field	Type	Description
symbol	string	Canonical symbol in `BASE-QUOTE` format.
exchanges	string[]	Exchange IDs that have this symbol live.

6.5 pong

{ "type": "pong" }

6.6 error

{ "type": "error", "message": "unknown channel" }

7. Channel Types

Prefix	Example	Description	Level Format
`top:`	`top:BTC-USDT`	BBO (best bid/offer). Exactly 1 level per side, aggregated across all exchanges. Depth parameter is ignored.	`[price, qty, orders]`
`consbook:`	`consbook:ETH-USDT`	Consolidated book. Multi-level aggregated across exchanges — levels at the same price are merged (quantities summed, order counts summed). No exchange attribution.	`[price, qty, orders]`
`fullbook:`	`fullbook:BTC-USDT`	Full book from all exchanges. Each level carries the source exchange ID. Best price across all exchanges at top.	`[price, qty, orders, exchange_id]`
`{exchange}:`	`binance:BTC-USDT`	Single exchange book. Only data from the specified exchange.	`[price, qty, orders]`

7.1 BBO Top-of-Book (`top:`)

Best bid and best offer aggregated across all exchanges. Always returns exactly 1 level per side. If multiple exchanges share the best price, quantities and order counts are summed. The depth parameter is ignored.

Use case: Ticker displays, BBO monitoring, lightweight price feeds.

7.2 Consolidated Book (`consbook:`)

Multi-level aggregated book. Merges levels at identical price points across exchanges. If Binance and Coinbase both have a bid at 83450.50, the aggregated level shows the combined quantity and order count. No exchange attribution. Price matching uses adaptive floating-point tolerance based on price magnitude.

Use case: Consolidated depth visualization, market microstructure analysis.

7.3 Full Book (`fullbook:`)

Merges order books from all exchanges into a single sorted book. Each level carries the exchange_id of its source exchange. This allows clients to see the global best bid/ask and which exchange offers it.

Use case: Cross-exchange arbitrage detection, global NBBO tracking, execution routing.

7.4 Single Exchange (`{exchange}:`)

Raw order book from a single exchange, normalized into canonical symbol format. No cross-exchange merging.

Use case: Exchange-specific trading, per-venue monitoring.

8. Supported Exchanges

#	ID	Name	Quote	Native Symbol Format	Markets
0	`binance`	Binance	USDT	BTCUSDT (concatenated)	Spot
1	`coinbase`	Coinbase	USD	BTC-USD (dash)	Advanced Trade
2	`okx`	OKX	USDT	BTC-USDT (dash)	Spot
3	`bybit`	Bybit	USDT	BTCUSDT (concatenated)	Spot
4	`kraken`	Kraken	USDT	BTC/USDT (slash)	Spot
5	`gemini`	Gemini	USD	BTCUSD (concatenated)	Spot
6	`cryptocom`	Crypto.com	USDT	BTC_USDT (underscore)	Spot
7	`gateio`	Gate.io	USDT	BTC_USDT (underscore)	Spot
8	`kucoin`	KuCoin	USDT	BTC-USDT (dash)	Spot
9	`upbit`	Upbit	USDT	USDT-BTC (reverse dash)	Spot
10	`bitget`	Bitget	USDT	BTCUSDT (concatenated)	Spot
11	`mexc`	MEXC	USDT	BTCUSDT (concatenated)	Spot
12	`htx`	HTX	USDT	btcusdt (lowercase concat)	Spot
13	`bitfinex`	Bitfinex	USD	tBTCUSD / tSHIB:USD	Spot
14	`bingx`	BingX	USDT	BTC-USDT (dash)	Spot
15	`phemex`	Phemex	USDT	sBTCUSDT (s-prefix concat)	Spot
16	`lbank`	LBank	USDT	btc_usdt (lowercase underscore)	Spot
17	`bitmart`	BitMart	USDT	BTC_USDT (underscore)	Spot
18	`coinex`	CoinEx	USDT	BTCUSDT (concatenated)	Spot
19	`ascendex`	AscendEX	USDT	BTC/USDT (slash)	Spot
20	`deribit`	Deribit	USD	BTC-PERPETUAL	Options & Futures

9. Symbol Format

The API uses a canonical symbol format: uppercase BASE-QUOTE separated by a hyphen.

Canonical	Description
`BTC-USDT`	Bitcoin / Tether
`ETH-USD`	Ethereum / US Dollar
`SOL-USDT`	Solana / Tether

Each exchange uses its own native symbol format internally. The API normalizes all symbols to the canonical format automatically.

Native format examples for BTC-USDT

Exchange	Native Format	Canonical
Binance	`BTCUSDT`	`BTC-USDT`
Coinbase	`BTC-USD`	`BTC-USD`
Kraken	`BTC/USDT`	`BTC-USDT`
Upbit	`USDT-BTC`	`BTC-USDT`
HTX	`btcusdt`	`BTC-USDT`
Bitfinex	`tBTCUSD`	`BTC-USD`
Phemex	`sBTCUSDT`	`BTC-USDT`
LBank	`btc_usdt`	`BTC-USDT`

10. Data Field Reference

Book Snapshot Fields

Field	Type	Description
type	string	Always `"snapshot"`.
channel	string	Channel identifier matching the subscription.
data.bids	array[]	Bid levels sorted descending by price. See level format.
data.asks	array[]	Ask levels sorted ascending by price. See level format.
data.ts	integer	Snapshot timestamp in milliseconds since Unix epoch (UTC).

Price Level Fields

Index	Field	Type	Unit	Description
0	price	float	Quote currency	Price level. Decimal precision adapts to magnitude.
1	qty	float	Base currency	Total quantity available at this price. Up to 8 significant figures.
2	orders	integer	Count	Number of resting orders at this price level.
3	exchange_id	string	—	Source exchange. Only in `fullbook:` channel.

Price Decimal Precision

Price Range	Decimals	Example
≥ 1,000	2	`83450.50`
≥ 10	3	`45.125`
≥ 1	4	`1.2345`
≥ 0.01	6	`0.012345`
< 0.01	8	`0.00001234`

11. Throttling & Performance

Parameter	Value
Update throttle	100ms per channel (configurable). Updates arriving faster are coalesced — the client always receives the latest state.
Wire-to-client latency	< 1ms typical (exchange WebSocket → parser → SHM ring → mdf_server → gateway → client)
Max subscriptions per connection	Unlimited
Max depth	100 levels per side

Coalescing: When a book updates faster than the throttle window, intermediate states are skipped. The client always receives a complete, consistent snapshot — never a partial update.

12. Error Codes

Message	Description
`missing op`	No `op` field in the client message.
`unknown op`	Unrecognized operation. Valid: `subscribe`, `unsubscribe`, `ping`, `exchanges`, `symbols`.
`missing channel`	Subscribe/unsubscribe without a `channel` field.
`unknown channel`	Invalid channel format. Expected `{type}:{SYMBOL}`.
`unknown symbol`	Symbol not found on any exchange.
`unknown exchange`	Exchange ID not recognized.
`already subscribed`	Duplicate subscription to the same channel.

13. Complete Examples

Example 1: Subscribe to full BTC book

�� Client sends:
{"op":"subscribe","channel":"fullbook:BTC-USDT","depth":5}

← Server responds:
{"type":"subscribed","channel":"fullbook:BTC-USDT"}

← Server pushes snapshots (every ~100ms):
{"type":"snapshot","channel":"fullbook:BTC-USDT","data":{
  "bids":[[83450.50,1.234,5,"binance"],[83450.25,0.891,3,"coinbase"],...],
  "asks":[[83451.00,0.750,2,"okx"],[83451.25,1.500,4,"bybit"],...],
  "ts":1712200000000}}

Example 2: Subscribe to single exchange

→ Client sends:
{"op":"subscribe","channel":"binance:ETH-USDT","depth":20}

← Server responds:
{"type":"subscribed","channel":"binance:ETH-USDT"}

← Snapshot (no exchange_id in levels):
{"type":"snapshot","channel":"binance:ETH-USDT","data":{
  "bids":[[3245.80,12.5,8],[3245.75,5.2,3],...],
  "asks":[[3245.85,8.1,4],[3245.90,15.3,6],...],
  "ts":1712200000123}}

Example 3: Discover available symbols

→ Client sends:
{"op":"exchanges"}

← Server responds:
{"type":"exchanges","data":[
  {"id":"binance","name":"Binance","quote":"USDT","symbols":145,"status":"live"},
  {"id":"coinbase","name":"Coinbase","quote":"USD","symbols":98,"status":"live"},
  ...]}

→ Client sends:
{"op":"symbols","quote":"USDT"}

← Server responds:
{"type":"symbols","data":[
  {"symbol":"BTC-USDT","exchanges":["binance","okx","bybit",...]},
  {"symbol":"ETH-USDT","exchanges":["binance","coinbase","okx",...]},
  ...]}

Example 4: Error handling

→ Client sends (invalid):
{"op":"subscribe","channel":"invalid"}

← Server responds:
{"type":"error","message":"unknown channel"}

14. Exchange Native WebSocket APIs

Reference documentation for the native WebSocket order book APIs of all 21 connected exchanges. Microverse normalizes these diverse protocols into the unified API described above.

Comparison Table

Exchange	Endpoint	Depth Channel	Model	Compression	Keepalive
AscendEX	`wss://ascendex.com/api/pro/v2/stream`	`depth:{SYM}`	Snapshot + incremental	None	Server ping, respond `{"op":"pong"}`
Binance	`wss://stream.binance.com:9443/ws`	`{sym}@depth`	Incremental + REST snapshot	None	Server ping (WebSocket frame)
BingX	`wss://open-api-ws.bingx.com/market`	`{SYM}@depth`	Snapshot + incremental	GZIP	Server ping/5s, echo pong
Bitfinex	`wss://api-pub.bitfinex.com/ws/2`	`book` (prec/freq/len)	Snapshot then incremental	None	Server heartbeat/15s
Bitget	`wss://ws.bitget.com/v2/ws/public`	`books` / `books5`	Snapshot (1/5/15) or incremental (full)	None	Client sends "ping"/30s
BitMart	`wss://ws-manager-compress.bitmart.com/api?protocol=1.1`	`spot/depth50:{SYM}`	Snapshot (depth50) or incremental (increase100)	Deflate	Client sends "ping" text
Bybit	`wss://stream.bybit.com/v5/public/spot`	`orderbook.{depth}.{sym}`	Snapshot then delta	None	Client ping/20s, server pong
Coinbase	`wss://advanced-trade-ws.coinbase.com`	`level2`	Snapshot then incremental	None	Server heartbeat channel
CoinEx	`wss://socket.coinex.com/v2/spot`	`depth.subscribe`	Configurable: full or incremental	ZIP	`server.ping` (60s timeout)
Crypto.com	`wss://stream.crypto.com/exchange/v1/market`	`book.{sym}.{depth}`	Snapshot or delta (configurable)	None	Heartbeat/30s, respond within 5s
Deribit	`wss://www.deribit.com/ws/api/v2`	`book.{inst}.{group}.{depth}.{interval}`	Snapshot + incremental (change_id)	None	`public/set_heartbeat` or `public/ping`
Gate.io	`wss://api.gateio.ws/ws/v4/`	`spot.order_book_update`	Incremental + REST snapshot	None	Client ping/15s
Gemini	`wss://api.gemini.com/v2/marketdata`	`l2_updates`	Snapshot then incremental	None	Server heartbeat/5s
HTX	`wss://api.huobi.pro/ws`	`market.{sym}.depth.step0`	Snapshot (depth) or incremental (MBP)	GZIP	Server `{"ping":ts}`/20s, echo `{"pong":ts}`
Kraken	`wss://ws.kraken.com/v2`	`book` (depth param)	Snapshot then incremental	None	Server ping, client pong
KuCoin	`wss://x-push-spot.kucoin.com`	`obu` (Pro) / `/spotMarket/level2Depth*`	Snapshot (5/50) or incremental	None	Ping/18s, timeout 10s
LBank	`wss://www.lbkex.net/ws/V2/`	`depth`	Snapshot only	None	Server ping, echo pong (1min)
MEXC	`wss://wbs-api.mexc.com/ws`	`[email protected]@{SYM}`	Incremental + REST snapshot	None	Must respond to server pings
OKX	`wss://ws.okx.com:8443/ws/v5/public`	`books` / `books5`	Snapshot then incremental	None	Client ping "ping"/30s
Phemex	`wss://ws.phemex.com`	`orderbook.subscribe`	Snapshot + incremental (60s re-snapshot)	None	Client ping <30s
Upbit	`wss://api.upbit.com/websocket/v1`	`orderbook`	Full snapshot each push	None	120s idle timeout

14.1 AscendEX

Endpoint

wss://ascendex.com/api/pro/v2/stream

{"op": "sub", "ch": "depth:BTC/USDT"}

Snapshot Request

{"op": "req", "action": "depth-snapshot", "args": {"symbol": "BTC/USDT"}}

Subscribe to depth:{SYMBOL} for incremental updates, then request depth-snapshot for initial state. Updates throttled at 300ms. Symbol format uses forward slash: BTC/USDT.

Parameter	Value
Max connections	300/IP total, 20/IP/account group
Rate limits	subscribe: 150/min, snapshot queries: 400-500/min
Keepalive	Server sends `ping`, respond with `{"op":"pong"}`

14.2 Binance

Endpoint

wss://stream.binance.com:9443/ws/btcusdt@depth

Subscribe (combined stream)

{"method": "SUBSCRIBE", "params": ["btcusdt@depth"], "id": 1}

Incremental updates via {symbol}@depth stream. Must fetch initial snapshot via REST GET /api/v3/depth?symbol=BTCUSDT&limit=1000 and synchronize using lastUpdateId. Apply updates where U <= lastUpdateId+1 <= u.

Parameter	Value
Max connections	5 per IP per 5 minutes
Max streams/conn	1024 (combined stream)
Keepalive	Server WebSocket-level ping; idle disconnect after 24h
Rate limit	10 messages/second

14.3 BingX

Endpoint

wss://open-api-ws.bingx.com/market

{"id": "<uuid>", "dataType": "BTC-USDT@depth"}

All responses are GZIP compressed — must decompress before parsing. Symbol format uses hyphen: BTC-USDT. Server sends heartbeat ping every ~5 seconds; client must respond with pong or connection drops.

Parameter	Value
Max subscriptions/conn	200
Compression	GZIP (all messages)
Keepalive	Server ping/5s, must echo pong

14.4 Bitfinex

Endpoint

wss://api-pub.bitfinex.com/ws/2

{
  "event": "subscribe",
  "channel": "book",
  "symbol": "tBTCUSD",
  "prec": "P0",
  "freq": "F0",
  "len": "25"
}

Precision: P0-P4 (5 to 1 sig figs). Frequency: F0 (real-time), F1 (2s batch). Length: 1, 25, 100, 250. Symbol prefix: t for trading pairs. Updates: COUNT=0 means delete level; AMOUNT sign indicates side (positive=bid, negative=ask).

Parameter	Value
Max connections	20 public/min
Max subscriptions/conn	25
Keepalive	Server heartbeat `[CHANNEL_ID, "hb"]` every 15s

14.5 Bitget

Endpoint

wss://ws.bitget.com/v2/ws/public

{
  "op": "subscribe",
  "args": [{"instType": "SPOT", "channel": "books5", "instId": "BTCUSDT"}]
}

Channels: books (full depth, incremental after first snapshot), books1/books5/books15 (snapshot each push). CRC32 checksum for integrity validation on books channel.

Parameter	Value
Max subscriptions/conn	1000
Rate limits	240 sub requests/hr, 10 msg/s
Keepalive	Client sends `"ping"` string every 30s

14.6 BitMart

Endpoint

wss://ws-manager-compress.bitmart.com/api?protocol=1.1

{"op": "subscribe", "args": ["spot/depth50:BTC_USDT"]}

Channels: spot/depth5, spot/depth50 (snapshots), spot/depth/increase100 (incremental). Symbol format uses underscore: BTC_USDT. Data is compressed (deflate).

Parameter	Value
Max connections/IP	10
Max subscriptions/conn	100
Rate limits	30 conn requests/min, 100 sub msg/10s
Keepalive	Client sends text `ping`, server responds `pong`

14.7 Bybit

Endpoint

wss://stream.bybit.com/v5/public/spot

{"op": "subscribe", "args": ["orderbook.50.BTCUSDT"]}

Depth: 1 (100ms), 50 (20ms), 200 (100ms). First message is snapshot ("type":"snapshot"), then deltas ("type":"delta"). Cross-sequence validation via seq field.

Parameter	Value
Max connections	500/5min per IP
Max subscriptions/conn	Varies by topic
Keepalive	Client sends `{"op":"ping"}` every 20s

14.8 Coinbase

Endpoint

wss://advanced-trade-ws.coinbase.com

{
  "type": "subscribe",
  "product_ids": ["BTC-USD"],
  "channel": "level2"
}

Initial snapshot followed by incremental updates. Updates have "side" ("bid"/"offer"), "price_level", "new_quantity". Quantity "0" = remove level. Requires HMAC-SHA256 signature for authentication (optional for public).

Parameter	Value
Max connections	750 per IP for public
Max subscriptions/conn	100 product_ids per channel
Keepalive	Server heartbeat channel every ~1s

14.9 CoinEx

Endpoint

wss://socket.coinex.com/v2/spot

{
  "method": "depth.subscribe",
  "params": {"market_list": [["BTCUSDT", 50, "0", true]]},
  "id": 1
}

Params: [market, limit, merge_interval, is_full]. is_full=true = full push (~200ms), is_full=false = incremental diffs. CRC32 checksum included. All data is ZIP compressed.

Parameter	Value
Depth levels	5, 10, 20, 50
Compression	ZIP (all messages)
Keepalive	`{"method":"server.ping"}`, 60s timeout

14.10 Crypto.com

Endpoint

wss://stream.crypto.com/exchange/v1/market

{
  "id": 1,
  "method": "subscribe",
  "params": {"channels": ["book.BTC_USD.50"]},
  "nonce": 1587523073344
}

Channel: book.{instrument}.{depth}. Depths: 10, 25, 50. Subscription type: SNAPSHOT (500ms) or SNAPSHOT_AND_UPDATE (100ms delta, recommended). Entries: [price, quantity, order_count]. Symbol format uses underscore: BTC_USD.

Parameter	Value
Rate limits	100 requests/s (market data)
Keepalive	Server heartbeat every 30s, respond within 5s with `respond-heartbeat`

14.11 Deribit

Endpoint

wss://www.deribit.com/ws/api/v2

{
  "jsonrpc": "2.0",
  "method": "public/subscribe",
  "params": {"channels": ["book.BTC-PERPETUAL.none.20.100ms"]},
  "id": 1
}

Channel: book.{instrument}.{group}.{depth}.{interval}. Groups: none, 1-25. Depth: 1, 10, 20. Interval: 100ms, agg2, raw. JSON-RPC 2.0 protocol. Uses change_id/prev_change_id for sequence tracking. Actions: "new", "change", "delete".

Parameter	Value
Max connections	32 per IP
Rate limits	200 msg/s (burst 300), 500 channels/subscription msg
Keepalive	`public/set_heartbeat` or `public/ping`

14.12 Gate.io

Endpoint

wss://api.gateio.ws/ws/v4/

{
  "time": 1606292218,
  "channel": "spot.order_book_update",
  "event": "subscribe",
  "payload": ["BTC_USDT", "100ms"]
}

Incremental updates with sequence IDs (u, U). Synchronize with REST snapshot GET /api/v4/spot/order_book?currency_pair=BTC_USDT&limit=100. Also available: spot.order_book (full snapshot mode). Symbol format uses underscore: BTC_USDT.

Parameter	Value
Update intervals	100ms, 1000ms
Rate limits	120 requests/min per connection
Keepalive	Client sends ping, server pong; 60s idle timeout

14.13 Gemini

Endpoint

wss://api.gemini.com/v2/marketdata

{
  "type": "subscribe",
  "subscriptions": [{"name": "l2", "symbols": ["BTCUSD"]}]
}

Initial snapshot with full book, then incremental l2_updates. Each update contains an array of ["buy"/"sell", price, quantity] changes. Quantity "0" = remove level. Symbol format: concatenated uppercase BTCUSD.

Parameter	Value
Max connections	Shared with REST rate limits
Keepalive	Server heartbeat every ~5s

14.14 HTX (Huobi)

Endpoints

wss://api.huobi.pro/ws        # market depth (snapshot)
wss://api.huobi.pro/feed      # MBP incremental (tick-by-tick)
wss://api-aws.huobi.pro/ws    # AWS (lower latency)

Subscribe (depth snapshot)

{"sub": "market.btcusdt.depth.step0", "id": "id1"}

Subscribe (MBP incremental)

{"sub": "market.btcusdt.mbp.150", "id": "id1"}

Depth steps: step0-step5 (price aggregation). MBP levels: 5, 20, 150, 400. MBP uses seqNum/prevSeqNum for sequencing. Symbols lowercase: btcusdt. All market data messages are GZIP compressed.

Parameter	Value
Compression	GZIP (all market WS data)
Keepalive	Server `{"ping": timestamp}` every 20s; respond `{"pong": timestamp}`

14.15 Kraken

Endpoint

wss://ws.kraken.com/v2

{
  "method": "subscribe",
  "params": {
    "channel": "book",
    "symbol": ["BTC/USDT"],
    "depth": 25
  }
}

Depth: 10, 25, 100, 500, 1000. Initial snapshot then incremental updates with CRC32 checksum. Symbol format uses slash: BTC/USDT.

Parameter	Value
Max connections	150 per IP
Max subscriptions/conn	Soft limit; recommended <100
Keepalive	Server ping, client responds with pong

14.16 KuCoin

Endpoint

# Must first obtain token via POST /api/v1/bullet-public
wss://x-push-spot.kucoin.com # Pro API

Subscribe (Pro API)

{
  "id": "1545910660739",
  "action": "SUBSCRIBE",
  "channel": "obu",
  "tradeType": "SPOT",
  "symbol": "BTC-USDT",
  "depth": "5"
}

Subscribe (Classic API)

{"type": "subscribe", "topic": "/spotMarket/level2Depth50:BTC-USDT", "response": true}

Token required (valid 24h, unauthenticated REST call). Pro API depth: 1, 5, 50, increment. Classic topics: /spotMarket/level2Depth5, /spotMarket/level2Depth50, /spotMarket/level2 (incremental).

Parameter	Value
Max subscriptions/conn	300 (Pro API)
Rate limits	100 msg/10s per connection
Keepalive	Ping every 18s, timeout 10s

14.17 LBank

Endpoint

wss://www.lbkex.net/ws/V2/

{"action": "subscribe", "subscribe": "depth", "depth": "100", "pair": "btc_usdt"}

Snapshot-only model: full book state pushed whenever the order book changes. Depth: 10, 50, 100. Symbol format: lowercase underscore btc_usdt.

Parameter	Value
Keepalive	Server sends `{"action":"ping","ping":"<uuid>"}`; respond `{"action":"pong","pong":"<uuid>"}` within 1 min

14.18 MEXC

Endpoint

wss://wbs-api.mexc.com/ws

{"op": "sub", "args": ["[email protected]@BTCUSDT"]}

Incremental diff depth. Must fetch REST snapshot GET /api/v3/depth?symbol=BTCUSDT&limit=5000 and synchronize using fromVersion/lastUpdateId. Symbols uppercase: BTCUSDT.

Parameter	Value
Max subscriptions/conn	30
Rate limits	100 msg/s
Connection validity	24h max; 60s inactivity disconnect
Keepalive	Must respond to server ping messages

14.19 OKX

Endpoint

wss://ws.okx.com:8443/ws/v5/public

{
  "op": "subscribe",
  "args": [{"channel": "books", "instId": "BTC-USDT"}]
}

Channels: books (400 levels, incremental after initial snapshot), books5 (5 levels, snapshot each push), books-l2-tbt (tick-by-tick), bbo-tbt (BBO). CRC32 checksum for books/books-l2-tbt. Symbol format: BTC-USDT.

Parameter	Value
Max connections	3 per IP per URL
Max subscriptions/conn	240
Keepalive	Client sends `"ping"` text every 30s

14.20 Phemex

Endpoint

wss://ws.phemex.com

{"id": 0, "method": "orderbook.subscribe", "params": ["sBTCUSDT"]}

Initial snapshot followed by incremental updates. Full re-snapshot sent every 60 seconds. Prices use scaled integer format (priceEp): divide by 10^8 for actual price. Spot symbols prefixed with s: sBTCUSDT.

Parameter	Value
Max connections	5 per client
Max subscriptions/conn	20
Rate limits	20 requests/s per connection
Keepalive	Client ping every <30s (recommended 5s)

14.21 Upbit

Endpoint

wss://api.upbit.com/websocket/v1

[
  {"ticket": "unique-uuid"},
  {"type": "orderbook", "codes": ["KRW-BTC", "KRW-ETH.5"]},
  {"format": "DEFAULT"}
]

Full snapshot each push (not incremental). Append .{count} for depth: 1, 5, 15, 30 (default). Symbol format is reversed: FIAT-CRYPTO (e.g. KRW-BTC). Format: DEFAULT (verbose) or SIMPLE (compact field names).

Parameter	Value
Rate limits	5 conn/s, 5 msg/s, 100 msg/min
Idle timeout	120s (send ping to keep alive)

Table of Contents

1. Overview

Key Features

2. Connection

Endpoint

Protocol

Quick Start

3. Authentication

4. Message Format

Client → Server

Server → Client

5. Client Messages

5.1 subscribe

Channel format

5.2 unsubscribe

5.3 ping

5.4 exchanges

5.5 symbols

6. Server Messages

6.1 snapshot

Full book (fullbook:) — with exchange attribution

BBO (top:), consolidated (consbook:), and single exchange — no attribution

Level array fields

Timestamp

6.2 subscribed / unsubscribed

6.3 exchanges response

6.4 symbols response

6.5 pong

6.6 error

7. Channel Types

7.1 BBO Top-of-Book (top:)

7.2 Consolidated Book (consbook:)

7.3 Full Book (fullbook:)

7.4 Single Exchange ({exchange}:)

8. Supported Exchanges

9. Symbol Format

Native format examples for BTC-USDT

10. Data Field Reference

Book Snapshot Fields

Price Level Fields

Price Decimal Precision

11. Throttling & Performance

12. Error Codes

13. Complete Examples

Example 1: Subscribe to full BTC book

Example 2: Subscribe to single exchange

Example 3: Discover available symbols

Example 4: Error handling

14. Exchange Native WebSocket APIs

Comparison Table

14.1 AscendEX

Endpoint

Subscribe

Snapshot Request

14.2 Binance

Endpoint

Subscribe (combined stream)

14.3 BingX

Endpoint

Subscribe

14.4 Bitfinex

Endpoint

Subscribe

14.5 Bitget

Endpoint

Subscribe

14.6 BitMart

Endpoint

Subscribe

14.7 Bybit

Endpoint

Subscribe

14.8 Coinbase

Endpoint

Subscribe

14.9 CoinEx

Endpoint

Subscribe

14.10 Crypto.com

Full book (`fullbook:`) — with exchange attribution

BBO (`top:`), consolidated (`consbook:`), and single exchange — no attribution

7.1 BBO Top-of-Book (`top:`)

7.2 Consolidated Book (`consbook:`)

7.3 Full Book (`fullbook:`)

7.4 Single Exchange (`{exchange}:`)