Create Username Challenge

Create the wallet-signing challenge for a Polymarket username create or update.

POST /v3/polymarket/profiles/username/challenge

Creates a one-time challenge for a user-owned EOA. The response contains:

• a Polymarket SIWE message to sign with personal_sign
• a PolyNode consent typed-data payload to sign with eth_signTypedData_v4
• derived deposit wallet and Safe addresses

The challenge expires after 10 minutes.

Request

{
  "address": "0xC3579b0C908F43d50C63951A30C6f72fCEA4F6A0",
  "username": "alice123",
  "action": "set_username"
}

Field	Type	Required	Description
address	string	Yes	User EOA address
username	string	Yes	Desired username
action	string	No	Must be set_username. Defaults to set_username.

Example

curl -X POST "https://api.polynode.dev/v3/polymarket/profiles/username/challenge" \
  -H "content-type: application/json" \
  -H "x-api-key: pn_live_..." \
  -d '{
    "address": "0xC3579b0C908F43d50C63951A30C6f72fCEA4F6A0",
    "username": "alice123",
    "action": "set_username"
  }'

Response

{
  "challenge_id": "pmprof_652e85a9839fe3e97348a72ff5018ef5",
  "address": "0xC3579b0C908F43d50C63951A30C6f72fCEA4F6A0",
  "username": "alice123",
  "action": "set_username",
  "expires_at": "2026-05-26T13:03:06Z",
  "polymarket": {
    "signature_type": "personal_sign",
    "message": "polymarket.com wants you to sign in with your Ethereum account:\n0xC3579b0C908F43d50C63951A30C6f72fCEA4F6A0\n\nWelcome to Polymarket! Sign to connect.\n\nURI: https://polymarket.com\nVersion: 1\nChain ID: 137\nNonce: 4b7d...\nIssued At: 2026-05-26T12:53:06.000Z\nExpiration Time: 2026-06-02T12:53:06.000Z",
    "fields": {
      "domain": "polymarket.com",
      "address": "0xC3579b0C908F43d50C63951A30C6f72fCEA4F6A0",
      "statement": "Welcome to Polymarket! Sign to connect.",
      "uri": "https://polymarket.com",
      "version": "1",
      "chainId": 137,
      "nonce": "4b7d...",
      "issuedAt": "2026-05-26T12:53:06.000Z",
      "expirationTime": "2026-06-02T12:53:06.000Z"
    }
  },
  "consent": {
    "signature_type": "typed_data_v4",
    "domain": {
      "name": "Polynode",
      "version": "1",
      "chainId": 137
    },
    "types": {
      "EIP712Domain": [
        { "name": "name", "type": "string" },
        { "name": "version", "type": "string" },
        { "name": "chainId", "type": "uint256" }
      ],
      "PolymarketProfileAction": [
        { "name": "action", "type": "string" },
        { "name": "address", "type": "address" },
        { "name": "username", "type": "string" },
        { "name": "challengeId", "type": "string" },
        { "name": "expiresAt", "type": "uint256" }
      ]
    },
    "primaryType": "PolymarketProfileAction",
    "message": {
      "action": "set_username",
      "address": "0xc3579b0c908f43d50c63951a30c6f72fcea4f6a0",
      "username": "alice123",
      "challengeId": "pmprof_652e85a9839fe3e97348a72ff5018ef5",
      "expiresAt": 1779800586
    }
  },
  "derived": {
    "deposit_wallet": "0xf6d30d58add6c6814d1b086ec543a16ab6cc9a31",
    "safe_address": "0xba2ef45d0fe68cee6351420b60fb554bbe91bf02",
    "safe_deployed": false
  }
}

Server checks

The endpoint:

• validates address and username format
• checks Polymarket username availability
• fetches a Gamma nonce
• builds the exact Polymarket SIWE message
• builds PolyNode consent typed data
• derives deposit wallet and Safe addresses
• checks whether the derived Safe is deployed on Polygon
• stores a one-time challenge under a 10 minute TTL

Errors

Status	Code	Meaning
400	invalid_address or invalid_username	Request validation failed
400	challenge_mismatch	Unsupported action
409	username_taken	Username is not available
429	rate_limited	Profile-specific rate limit exceeded
502	upstream_unavailable	Polymarket, Gamma, or Polygon RPC failed