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Authentication for gRPC Streaming

gRPC streaming connections use JWT (JSON Web Token) authentication obtained from the REST API. This guide explains the complete authentication flow using Python.

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Authentication Architecture

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Step 1: Obtain JWT Token from REST API

Before establishing any gRPC streaming connection, you must first authenticate via the REST API.

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Login Request

curl "https://traderapi.us-east-1.privatelink.preprod.polymarketexchange.com/auth/v1beta1/login" -H "Host: rest.preprod.polymarketexchange.com" -H "accept: application/json" -H "content-type: application/json" --data '{"password":"<password>","username":"<username>"}'

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Login Response

{
  "access_token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "refresh_token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "access_expiration_time": "2025-01-18T12:00:00Z",
  "refresh_expiration_time": "2025-01-19T12:00:00Z"
}
Token Fields:
  • access_token: Use this for gRPC authentication
  • refresh_token: Use this to obtain a new access token before expiration
  • access_expiration_time: When the access token expires
  • refresh_expiration_time: When the refresh token expires

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Step 2: Attach Token to gRPC Metadata

Once you have the access token, include it in the gRPC metadata for every streaming connection. 
import grpc
from connamara.ep3.v1beta1 import market_data_pb2_grpc

# Create secure channel
credentials = grpc.ssl_channel_credentials()
channel = grpc.secure_channel('traderapi.us-east-1.privatelink.preprod.polymarketexchange.com:443', credentials)

# Create stub
stub = market_data_pb2_grpc.MarketDataSubscriptionAPIStub(channel)

# Create metadata with authorization token
metadata = [
    ('authorization', access_token)
]

# Make streaming call with metadata
response_stream = stub.CreateMarketDataSubscription(request, metadata=metadata)
The metadata key must be authorization (lowercase). The value is the raw JWT token string.

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Handling Authentication Errors

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Common Authentication Errors

Error CodeDescriptionSolution
UNAUTHENTICATEDToken is invalid or missingVerify token in metadata, re-login if expired
PERMISSION_DENIEDToken is valid but lacks permissionsCheck user permissions with support
UNAVAILABLECannot reach authentication serviceCheck network connectivity, retry with backoff

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Next Steps

Market Data Streaming

Learn how to stream market data

Order Streaming

Subscribe to order updates

Error Handling

Handle errors and implement reconnection

Code Examples

See complete working examples