Polymarket Real-Time WebSocket

Connect to the Polymarket WebSocket for real-time price, orderbook, and trade updates.

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Connection

Connect to the WebSocket endpoint:

Code sample:

• const ws = new WebSocket('wss://api.delphiterminal.co/ws/poly');

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Subscribing to Markets

Once connected, send a JSON message to subscribe to Polymarket data using their condition_id:

Code sample:

• {
• "action": "subscribe",
• "condition_ids": ["0x00000977017fa72fb6b1908ae694000d3b51f442c2552656b10bdbbfd16ff707"],
• "message_types": ["prices", "orderbook", "trades"]
• }

Subscription Fields

Field	Type	Required	Description
action	string	Yes	subscribe or unsubscribe
condition_ids	array	Yes	Array of Polymarket condition identifiers (hex strings starting with 0x)
message_types	array	No	["prices"], ["orderbook"], ["trades"], or any combination. Defaults to prices and orderbook if omitted

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Unsubscribing

Code sample:

• {
• "action": "unsubscribe",
• "condition_ids": ["0x00000977017fa72fb6b1908ae694000d3b51f442c2552656b10bdbbfd16ff707"]
• }

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Message Types

Price Messages

Real-time price updates for subscribed markets:

Code sample:

• {
• "type": "prices",
• "data": {
• "exchange": "poly",
• "condition_id": "0x00000977017fa72fb6b1908ae694000d3b51f442c2552656b10bdbbfd16ff707",
• "price": 0.992,
• "last_update": "2026-02-04T15:30:00Z"
• }
• }

Orderbook Messages

Real-time orderbook snapshots for subscribed markets:

Code sample:

• {
• "type": "orderbook",
• "data": {
• "snapshot_time": "2026-02-04T15:30:00Z",
• "exchange": "poly",
• "market_id": "0x1234abcd5678efgh",
• "condition_id": "0x00000977017fa72fb6b1908ae694000d3b51f442c2552656b10bdbbfd16ff707",
• "bid_side": [0.55, 0.54, 0.53, 0.52, 0.51],
• "ask_side": [0.56, 0.57, 0.58, 0.59, 0.60],
• "original_last_update": "2026-02-04T15:29:59Z"
• }
• }

Trade Messages

Real-time trade executions for subscribed markets:

Code sample:

• {
• "type": "trades",
• "data": {
• "exchange": "poly",
• "condition_id": "0x00000977017fa72fb6b1908ae694000d3b51f442c2552656b10bdbbfd16ff707",
• "token_id": "0x123...",
• "market_id": "0xabc...",
• "price": 0.65,
• "size": 100.5,
• "side": "buy",
• "last_update": "2026-02-04T15:30:00Z"
• }
• }

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Full JavaScript Example

Code sample:

• const ws = new WebSocket('wss://api.delphiterminal.co/ws/poly');
• ws.onopen = () => {
• console.log('Connected to Polymarket WebSocket');
• // Subscribe to markets
• ws.send(JSON.stringify({
• action: 'subscribe',
• condition_ids: ['0x00000977017fa72fb6b1908ae694000d3b51f442c2552656b10bdbbfd16ff707'],
• message_types: ['prices', 'orderbook', 'trades']
• }));
• };
• ws.onmessage = (event) => {
• const data = JSON.parse(event.data);
• if (data.type === 'prices') {
• console.log('Price update:', data.data);
• } else if (data.type === 'orderbook') {
• console.log('Orderbook update:', data.data);
• } else if (data.type === 'trades') {
• console.log('Trade:', data.data);
• }
• };
• ws.onclose = () => {
• console.log('Disconnected from WebSocket');
• };
• ws.onerror = (error) => {
• console.error('WebSocket error:', error);
• };

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Connection Details

Property	Value
Protocol	WebSocket (wss://)
Keepalive	Ping every 54 seconds
Timeout	60 seconds without pong
Max Message Size	512 KB

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Notes

• No authentication required for WebSocket connection
• You must use condition_id (Polymarket condition identifier) to subscribe
• Messages are only sent for markets you have explicitly subscribed to
• Multiple markets can be subscribed in a single message
• Subscribe to specific message types to reduce message volume
• Trades must be explicitly requested (not included in default subscription)
• Orderbook updates are high-frequency - consider filtering client-side if needed

GET /ws/poly

Response

101

WebSocket connection upgraded successfully