WebSocket Streaming

The server bridges streaming onto a local WebSocket at ws://127.0.0.1:25520/v1/events. Connect, send one JSON envelope per command, and receive one JSON message per event.

Subscribe envelope

{
    "msg_type": "STREAM",
    "sec_type": "STOCK",
    "req_type": "QUOTE",
    "add": true,
    "id": 1,
    "contract": {"symbol": "AAPL"}
}

Field	Values
sec_type	STOCK, OPTION, INDEX
req_type	QUOTE, TRADE, OHLC, OPEN_INTEREST, FULL_TRADES, FULL_OPEN_INTEREST
add	true subscribes, false unsubscribes
id	Your request id; echoed in the acknowledgement
contract	Omit for FULL_* streams

Option contracts carry the four-tuple, with the strike in thousandths of a dollar (the one wire-format exception to the dollars-everywhere rule — see Symbology):

{"symbol": "SPY", "expiration": 20250321, "strike": 570000, "right": "C"}

{"msg_type": "STOP", "id": 2} removes every active stream at once. Each command is acknowledged:

{ "header": { "type": "REQ_RESPONSE", "response": "OK", "req_id": 1 } }

Invalid commands answer with "response": "ERROR" and a message naming the offending field.

Event messages

Events arrive as JSON with a header.type of QUOTE, TRADE, OHLC, or OPEN_INTEREST, plus a STATUS heartbeat every second. OHLC bars flow automatically on any active trade subscription (disable with the server's --no-ohlcvc flag).

Try it

websocat ws://127.0.0.1:25520/v1/events
{"msg_type": "STREAM", "sec_type": "OPTION", "req_type": "TRADE", "id": 1, "add": true, "contract": {"symbol": "SPY", "expiration": 20250321, "strike": 570000, "right": "C"}}

Limits

• One client at a time. A second connection takes over the stream; the first receives a Close frame (code 1000, reason replaced by a new client connection). Run one server instance per consumer for multi-client setups.
• Text frames are capped at 4 KiB — far above any legitimate envelope.
• Programmatic consumers should prefer the SDK streaming surface, which adds typed events, automatic reconnect, and drop monitoring.