Exchange Integration: Polymarket US

[AshishMBakshi]

Feature Request: Add Support for Polymarket US Exchange API

Add native support for the Polymarket US Exchange (Retail API) to PMXT, enabling trading on the regulated U.S. platform alongside the existing Polymarket global integration.

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Motivation

Polymarket now offers a CFTC-regulated U.S. exchange with a distinct, account-based API. Supporting this API would:

• Enable U.S. users to trade in a compliant fashion
• Provide a unified interface across crypto-native and US-regulated environments

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Key Architectural Differences (vs current Polymarket integration)

1. Authentication & Identity

• All endpoints require authentication (no public endpoints)
• Requires:
  • API key (X-PM-Access-Key)
  • Timestamp (X-PM-Timestamp)
  • Ed25519 request signatures (X-PM-Signature)

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2. Account-Based (Non-Wallet) Model

• No wallet signing or on-chain identity
• Users interact via:
  • custodial trading accounts
  • balances, positions, and orders tied to account
• Includes funding rails:
  • ACH, card, Apple Pay deposits
  • withdrawals and funding status

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3. API Structure (Retail API)

• ~23 REST endpoints + 2 WebSocket endpoints
• Core categories:
  • Markets / Events / Series
  • Orders (create, cancel, query)
  • Portfolio (positions, activity)
  • Account (balances)

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4. WebSocket Design

• /v1/ws/markets → real-time market data
• /v1/ws/private → orders, positions, balances

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Suggested Architecture

• Create a separate exchange in PMXT:

  • pmxt/exchanges/polymarket_us/

• Do NOT reuse global Polymarket adapter due to:

  • different auth model (wallet vs account)
  • different transport/security model

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References

• https://docs.polymarket.us/

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Labels (suggested)

enhancement, exchange-support, polymarket, api

[AshishMBakshi]

Polymarket has a US Python SDK here: https://github.com/Polymarket/polymarket-us-python