PolymarketDocumentation/docs/developers/builders/relayer-client.md

Documentation Index

Fetch the complete documentation index at: https://docs.polymarket.com/llms.txt Use this file to discover all available pages before exploring further.

Gasless Transactions

Execute onchain operations without paying gas fees

Polymarket's Relayer Client enables gasless transactions for your users. Instead of requiring users to hold POL for gas, Polymarket's infrastructure pays all transaction fees. This creates a seamless experience where users only need USDC.e to trade.

How It Works

The relayer acts as a transaction sponsor:

1. Your app creates a transaction
2. The user signs it with their private key
3. Your app sends it to Polymarket's relayer
4. The relayer submits it onchain and pays the gas fee
5. The transaction executes from the user's wallet

Gasless transactions require **Builder Program** membership. You'll need Builder API credentials to authenticate with the relayer.

What's Covered

Polymarket pays gas for all operations routed through the relayer:

Operation	Description
Wallet deployment	Deploy Safe or Proxy wallets for new users
Token approvals	Approve contracts to spend USDC.e or outcome tokens
CTF operations	Split, merge, and redeem positions
Transfers	Move tokens between addresses

Prerequisites

Before using the relayer, you need:

Requirement	Source
Builder API credentials	Builder Profile
User's private key or signer	Your wallet integration
USDC.e balance	For trading (not for gas)

Installation

```bash npm theme={null} npm install @polymarket/builder-relayer-client @polymarket/builder-signing-sdk ```

pip install py-builder-relayer-client py-builder-signing-sdk

Client Setup

Initialize the relayer client with your signing configuration:

Use local signing when your backend handles all transactions securely.

<CodeGroup>
  ```typescript TypeScript theme={null}
  import { createWalletClient, http, Hex } from "viem";
  import { privateKeyToAccount } from "viem/accounts";
  import { polygon } from "viem/chains";
  import { RelayClient } from "@polymarket/builder-relayer-client";
  import { BuilderConfig } from "@polymarket/builder-signing-sdk";

  const account = privateKeyToAccount(process.env.PRIVATE_KEY as Hex);
  const wallet = createWalletClient({
    account,
    chain: polygon,
    transport: http(process.env.RPC_URL),
  });

  const builderConfig = new BuilderConfig({
    localBuilderCreds: {
      key: process.env.POLY_BUILDER_API_KEY!,
      secret: process.env.POLY_BUILDER_SECRET!,
      passphrase: process.env.POLY_BUILDER_PASSPHRASE!,
    },
  });

  const client = new RelayClient(
    "https://relayer-v2.polymarket.com/",
    137,
    wallet,
    builderConfig,
  );
  ```

  ```python Python theme={null}
  import os
  from py_builder_relayer_client.client import RelayClient
  from py_builder_signing_sdk import BuilderConfig, BuilderApiKeyCreds

  builder_config = BuilderConfig(
      local_builder_creds=BuilderApiKeyCreds(
          key=os.getenv("POLY_BUILDER_API_KEY"),
          secret=os.getenv("POLY_BUILDER_SECRET"),
          passphrase=os.getenv("POLY_BUILDER_PASSPHRASE"),
      )
  )

  client = RelayClient(
      "https://relayer-v2.polymarket.com",
      137,
      os.getenv("PRIVATE_KEY"),
      builder_config
  )
  ```
</CodeGroup>

Use remote signing to keep credentials on a secure server you control.

**Your signing server** receives request details and returns authentication headers:

<CodeGroup>
  ```typescript Server (TypeScript) theme={null}
  import {
    buildHmacSignature,
    BuilderApiKeyCreds,
  } from "@polymarket/builder-signing-sdk";

  const BUILDER_CREDENTIALS: BuilderApiKeyCreds = {
    key: process.env.POLY_BUILDER_API_KEY!,
    secret: process.env.POLY_BUILDER_SECRET!,
    passphrase: process.env.POLY_BUILDER_PASSPHRASE!,
  };

  // POST /sign endpoint
  export async function handleSignRequest(request) {
    const { method, path, body } = await request.json();
    const timestamp = Date.now().toString();

    const signature = buildHmacSignature(
      BUILDER_CREDENTIALS.secret,
      parseInt(timestamp),
      method,
      path,
      body,
    );

    return {
      POLY_BUILDER_SIGNATURE: signature,
      POLY_BUILDER_TIMESTAMP: timestamp,
      POLY_BUILDER_API_KEY: BUILDER_CREDENTIALS.key,
      POLY_BUILDER_PASSPHRASE: BUILDER_CREDENTIALS.passphrase,
    };
  }
  ```

  ```python Server (Python) theme={null}
  import os
  import time
  from py_builder_signing_sdk.signing.hmac import build_hmac_signature
  from py_builder_signing_sdk import BuilderApiKeyCreds

  BUILDER_CREDENTIALS = BuilderApiKeyCreds(
      key=os.environ["POLY_BUILDER_API_KEY"],
      secret=os.environ["POLY_BUILDER_SECRET"],
      passphrase=os.environ["POLY_BUILDER_PASSPHRASE"],
  )

  # POST /sign endpoint
  def handle_sign_request(method: str, path: str, body: str):
      timestamp = str(int(time.time()))

      signature = build_hmac_signature(
          BUILDER_CREDENTIALS.secret,
          timestamp,
          method,
          path,
          body
      )

      return {
          "POLY_BUILDER_SIGNATURE": signature,
          "POLY_BUILDER_TIMESTAMP": timestamp,
          "POLY_BUILDER_API_KEY": BUILDER_CREDENTIALS.key,
          "POLY_BUILDER_PASSPHRASE": BUILDER_CREDENTIALS.passphrase,
      }
  ```
</CodeGroup>

**Your client** points to your signing server:

<CodeGroup>
  ```typescript Client (TypeScript) theme={null}
  import { RelayClient } from "@polymarket/builder-relayer-client";
  import { BuilderConfig } from "@polymarket/builder-signing-sdk";

  const builderConfig = new BuilderConfig({
    remoteBuilderConfig: {
      url: "https://your-server.com/sign",
    },
  });

  const client = new RelayClient(
    "https://relayer-v2.polymarket.com/",
    137,
    wallet,
    builderConfig,
  );
  ```

  ```python Client (Python) theme={null}
  from py_builder_relayer_client.client import RelayClient
  from py_builder_signing_sdk import BuilderConfig, RemoteBuilderConfig

  builder_config = BuilderConfig(
      remote_builder_config=RemoteBuilderConfig(
          url="https://your-server.com/sign"
      )
  )

  client = RelayClient(
      "https://relayer-v2.polymarket.com",
      137,
      private_key,
      builder_config
  )
  ```
</CodeGroup>

Never expose Builder API credentials in client-side code. Use environment variables or a secrets manager.

Relayer Authentication Headers

All requests to the relayer must include these authentication headers:

Header	Description
POLY_BUILDER_API_KEY	Your Builder API key
POLY_BUILDER_TIMESTAMP	Unix timestamp
POLY_BUILDER_PASSPHRASE	Your Builder passphrase
POLY_BUILDER_SIGNATURE	HMAC-SHA256 signature

The SDKs handle header generation automatically when you provide your credentials via BuilderConfig.

Wallet Types

Choose a wallet type when initializing the client:

Type	Deployment	Best For
Safe	Call deploy() before first transaction	Most builder integrations
Proxy	Auto-deploys on first transaction	Magic Link users

```typescript Safe Wallet (TypeScript) theme={null} import { RelayClient, RelayerTxType } from "@polymarket/builder-relayer-client";

const client = new RelayClient( "https://relayer-v2.polymarket.com/", 137, wallet, builderConfig, RelayerTxType.SAFE, );

// Deploy before first transaction const response = await client.deploy(); const result = await response.wait(); console.log("Safe Address:", result?.proxyAddress);

```python Safe Wallet (Python) theme={null}
from py_builder_relayer_client.client import RelayClient

# client initialized with builder_config (see Client Setup above)

# Deploy before first transaction
response = client.deploy()
result = response.wait()
print("Safe Address:", result.get("proxyAddress"))

import { RelayClient, RelayerTxType } from "@polymarket/builder-relayer-client";

const client = new RelayClient(
  "https://relayer-v2.polymarket.com/",
  137,
  wallet,
  builderConfig,
  RelayerTxType.PROXY,
);

// No deploy needed - auto-deploys on first transaction

from py_builder_relayer_client.client import RelayClient

# client initialized with builder_config (see Client Setup above)
# No deploy needed - auto-deploys on first transaction

Executing Transactions

Use the execute method to send transactions through the relayer:

interface Transaction {
  to: string; // Target contract address
  data: string; // Encoded function call
  value: string; // POL to send (usually "0")
}

const response = await client.execute(transactions, "Description");
const result = await response.wait();

Token Approval

Approve contracts to spend tokens:

```typescript TypeScript theme={null} import { encodeFunctionData, maxUint256 } from "viem";

const USDC = "0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174"; const CTF = "0x4D97DCd97eC945f40cF65F87097ACe5EA0476045";

const approveTx = { to: USDC, data: encodeFunctionData({ abi: [ { name: "approve", type: "function", inputs: [ { name: "spender", type: "address" }, { name: "amount", type: "uint256" }, ], outputs: [{ type: "bool" }], }, ], functionName: "approve", args: [CTF, maxUint256], }), value: "0", };

const response = await client.execute([approveTx], "Approve USDC.e for CTF"); await response.wait();

```python Python theme={null}
from web3 import Web3

USDC = "0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174"
CTF = "0x4D97DCd97eC945f40cF65F87097ACe5EA0476045"
MAX_UINT256 = 2**256 - 1

approve_tx = {
    "to": USDC,
    "data": Web3().eth.contract(
        address=USDC,
        abi=[{
            "name": "approve",
            "type": "function",
            "inputs": [
                {"name": "spender", "type": "address"},
                {"name": "amount", "type": "uint256"}
            ],
            "outputs": [{"type": "bool"}]
        }]
    ).encode_abi(abi_element_identifier="approve", args=[CTF, MAX_UINT256]),
    "value": "0"
}

response = client.execute([approve_tx], "Approve USDC.e for CTF")
response.wait()

Redeem Positions

Exchange winning tokens for USDC.e after market resolution:

```typescript TypeScript theme={null} import { encodeFunctionData } from "viem";

const redeemTx = { to: CTF_ADDRESS, data: encodeFunctionData({ abi: [ { name: "redeemPositions", type: "function", inputs: [ { name: "collateralToken", type: "address" }, { name: "parentCollectionId", type: "bytes32" }, { name: "conditionId", type: "bytes32" }, { name: "indexSets", type: "uint256[]" }, ], outputs: [], }, ], functionName: "redeemPositions", args: [collateralToken, parentCollectionId, conditionId, indexSets], }), value: "0", };

const response = await client.execute([redeemTx], "Redeem positions"); await response.wait();

```python Python theme={null}
CTF = "0x4D97DCd97eC945f40cF65F87097ACe5EA0476045"

redeem_tx = {
    "to": CTF,
    "data": Web3().eth.contract(
        address=CTF,
        abi=[{
            "name": "redeemPositions",
            "type": "function",
            "inputs": [
                {"name": "collateralToken", "type": "address"},
                {"name": "parentCollectionId", "type": "bytes32"},
                {"name": "conditionId", "type": "bytes32"},
                {"name": "indexSets", "type": "uint256[]"}
            ],
            "outputs": []
        }]
    ).encode_abi(
        abi_element_identifier="redeemPositions",
        args=[collateral_token, parent_collection_id, condition_id, index_sets]
    ),
    "value": "0"
}

response = client.execute([redeem_tx], "Redeem positions")
response.wait()

Batch Transactions

Execute multiple operations atomically in a single call:

```typescript TypeScript theme={null} const approveTx = { to: USDC, data: encodeFunctionData({ abi: erc20Abi, functionName: "approve", args: [CTF, maxUint256], }), value: "0", };

const transferTx = { to: USDC, data: encodeFunctionData({ abi: erc20Abi, functionName: "transfer", args: [recipientAddress, parseUnits("50", 6)], }), value: "0", };

// Both execute atomically const response = await client.execute( [approveTx, transferTx], "Approve and transfer", ); await response.wait();

```python Python theme={null}
approve_tx = {
    "to": USDC,
    "data": contract.encode_abi(
        abi_element_identifier="approve",
        args=[CTF, MAX_UINT256]
    ),
    "value": "0"
}

transfer_tx = {
    "to": USDC,
    "data": contract.encode_abi(
        abi_element_identifier="transfer",
        args=[recipient_address, 50 * 10**6]
    ),
    "value": "0"
}

# Both execute atomically
response = client.execute([approve_tx, transfer_tx], "Approve and transfer")
response.wait()

Batching reduces latency and ensures all transactions succeed or fail together.

Transaction States

Track transaction progress through these states:

State	Terminal	Description
STATE_NEW	No	Transaction received by relayer
STATE_EXECUTED	No	Submitted onchain
STATE_MINED	No	Included in a block
STATE_CONFIRMED	Yes	Finalized successfully
STATE_FAILED	Yes	Failed permanently
STATE_INVALID	Yes	Rejected as invalid

Contract Addresses

See Contract Addresses for all Polymarket smart contract addresses on Polygon.

Resources

• Builder Relayer Client (TypeScript)
• Builder Relayer Client (Python)
• Builder Signing SDK (TypeScript)
• Builder Signing SDK (Python)

Next Steps

Learn about capital-efficient trading for multi-outcome events. Understand token operations like split, merge, and redeem.