Authentication - ParlayX API

The orderbook stream lives at a single endpoint:

wss://wss.parlayx.com/v1/orderbook

Authentication happens during the WebSocket upgrade — there is no separate login message and no token to refresh mid-stream. You either open the connection authenticated, or the upgrade is rejected before the socket opens.

Stream keys

WebSocket connections authenticate with a stream API key, which is distinct from your REST API key. Stream keys look like:

parx_stream_<hex>_<checksum>

One stream key authenticates every connection your account opens, up to your connection limit. Stream keys are currently issued by ParlayX in a closed release. If you don’t have one yet and are interested in using this service, reach out to us.

Supplying the key

Supply your key one of three ways, in order of preference:

#	Method	How
1	Subprotocol (preferred)	`Sec-WebSocket-Protocol: parlayx.v1, key.<rawKey>`
2	Authorization header	`Authorization: Bearer <rawKey>`
3	Query parameter (last resort)	`?api_key=<rawKey>`

Prefer the subprotocol or header. The ?api_key= query parameter is supported as a fallback for clients that can’t set headers, but query strings are commonly written to logs and proxies along the way — avoid it when you can.

import WebSocket from "ws";

const KEY = process.env.PARLAYX_STREAM_KEY;

// Preferred: pass the key as a subprotocol.
const ws = new WebSocket("wss://wss.parlayx.com/v1/orderbook", [
  "parlayx.v1",
  `key.${KEY}`,
]);

// Alternative: Authorization header.
// const ws = new WebSocket("wss://wss.parlayx.com/v1/orderbook", {
//   headers: { Authorization: `Bearer ${KEY}` },
// });

Handshake responses

The outcome of authentication is an HTTP status on the upgrade request, before any frame is sent:

Status	Meaning	What to do
`101`	Switching Protocols — the connection is open.	Wait for the `welcome` frame.
`401`	The key is missing or invalid.	Fix the key. Don’t retry the same key.
`429`	Your account is at its `maxConnections` limit.	Close a connection you no longer need; retrying alone won’t help.
`503`	The gateway is at capacity.	Back off briefly and retry — you’ll be routed to fresh capacity.

Once the upgrade succeeds the server immediately sends a welcome frame. From there, see Subscriptions & markets to start streaming.

​Stream keys

​Supplying the key

​Handshake responses

Stream keys

Supplying the key

Handshake responses