Polymarket Funding API

Fund an agent's Polymarket deposit wallet from its own Base USDC in a single x402 call — gaslessly (the agent never needs Base ETH) and non-custodially (BlockRun never receives or holds the principal).

This is the one on-chain money-movement BlockRun performs for prediction markets. It is deliberately constrained to Polymarket: the destination is validated to be the Polymarket bridge address for the caller's own vault, so this is not a general-purpose transfer relay. For market data (prices, orderbooks, positions, wallet analytics) see the Prediction Markets API.

How it works

The agent signs two EIP-3009 (transferWithAuthorization) USDC authorizations and sends both in one request:

1. Deposit — the agent's USDC → the Polymarket bridge address for its vault.
2. Fee — $0.011 USDC → the BlockRun treasury (the standard x402 payment).

BlockRun then:

1. Verifies the $0.011 fee authorization and guards it against replay.
2. Validates that recipient really is the Polymarket bridge deposit address for the caller's depositWallet (live lookup against the bridge). A mismatch is rejected before any settlement.
3. Hands the deposit authorization to the CDP facilitator, which broadcasts it and pays the gas. The USDC settles directly to the bridge — BlockRun is never in the flow of funds.
4. Only after the deposit is confirmed on-chain does BlockRun charge the $0.011 fee.
5. The Polymarket bridge wraps the USDC → pUSD and credits the agent's vault on Polygon.

A deposit that does not confirm is never billed. The fee is charged only after the deposit settles on-chain.

Networks

This call is cross-chain: you sign and move USDC on Base, and it lands as pUSD in your Polymarket vault on Polygon.

Both authorizations you sign — the $0.011 fee and the deposit — are Base USDC; you never touch Polygon or hold Base ETH for gas. The Polymarket bridge wraps the deposited USDC to pUSD and credits your vault on Polygon.

Pricing

Maximum deposit per call: $10,000 (POLYMARKET_FUND_MAX_USD).

POST /api/v1/polymarket/fund

Request body

The $0.011 fee authorization travels in the standard X-Payment header, exactly like every other paid BlockRun endpoint.

Discovery (402)

Call the endpoint with no X-Payment header to receive the machine-readable payment requirement and body schema:

curl -X POST https://blockrun.ai/api/v1/polymarket/fund

{
  "x402Version": 2,
  "accepts": [{ "scheme": "exact", "network": "eip155:8453", "amount": "11000", "asset": "0x8335…", "payTo": "0x…", "maxTimeoutSeconds": 300 }],
  "error": "Payment Required",
  "message": "This endpoint requires an x402 fee payment ($0.0110). Include the signed deposit authorization in the body.",
  "endpoint": "/api/v1/polymarket/fund",
  "method": "POST",
  "description": "Gaslessly fund your Polymarket deposit wallet: …",
  "price": { "amount": "0.0110", "currency": "USD" },
  "body_fields": {
    "depositWallet": { "type": "string", "required": true, "description": "Your Polymarket deposit wallet address" },
    "recipient": { "type": "string", "required": true, "description": "The Polymarket bridge address for your vault (from bridge /deposit)" },
    "amountMicro": { "type": "string", "required": true, "description": "Deposit amount in micro-USDC (6 decimals) — must equal your signed authorization value" },
    "depositAuthorization": { "type": "string", "required": true, "description": "base64 x402 payload: your EIP-3009 signed USDC transfer to `recipient`" }
  },
  "paymentInfo": { "network": "base", "asset": "USDC", "x402Version": 2 }
}

The x402 requirements (amount 11000 micro-USDC, exact scheme on Base) are also in the X-Payment-Required / PAYMENT-REQUIRED headers and WWW-Authenticate: X402 requirements="…".

Success (200)

{
  "success": true,
  "funded": false,
  "creditPending": true,
  "status": "deposit_submitted",
  "deposit": {
    "txHash": "0x…",
    "amountUsd": 25,
    "recipient": "0x…",
    "network": "base"
  },
  "fee": { "amountUsd": 0.01, "txHash": "0x…", "settled": true },
  "note": "Deposit submitted to the Polymarket bridge and confirmed on Base. The bridge credits pUSD to your Polygon vault asynchronously — usually within minutes, occasionally 30+. This endpoint cannot confirm the Polygon-side credit; poll your vault balance until pUSD appears."
}

The confirmed deposit transaction hash is also returned in the X-Deposit-Tx response header; the fee receipt is in X-Payment-Receipt.

:::warning Settlement is asynchronous success: true means the deposit was submitted to the bridge and confirmed on Base — and the $0.011 fee charged. It does not mean your vault is funded yet: funded is false and creditPending is true. The Polymarket bridge credits pUSD on Polygon off-chain and asynchronously — usually within minutes, occasionally 30+ minutes. There is no on-chain bridge message to poll; check your Polygon vault's pUSD balance until it lands. Very small deposits and non-standard deposit wallets may take longer or require a real (setup-derived) vault. :::

Errors

Every non-2xx response that could otherwise be ambiguous states explicitly whether your USDC moved and whether the fee was charged. The fee is charged only on a confirmed deposit.

Example

curl -X POST https://blockrun.ai/api/v1/polymarket/fund \
  -H "X-Payment: <base64 signed $0.011 fee authorization>" \
  -H "Content-Type: application/json" \
  -d '{
    "depositWallet": "0xYourVaultOwner…",
    "recipient": "0xPolymarketBridge…",
    "amountMicro": "25000000",
    "depositAuthorization": "<base64 signed USDC->bridge authorization>"
  }'

With the MCP, the agent does the two-signature dance for you:

Fund my Polymarket wallet with $25 from my Base USDC.

Safety & design

• Deposit-then-fee ordering — the fee is billed only after the deposit confirms on-chain, so a failed or reverted deposit is never charged.
• Polymarket-only — recipient must be your own vault's bridge address, verified live before any settlement. This is not a general transfer relay.
• Non-custodial — the deposit settles directly to the bridge via the CDP facilitator; BlockRun never receives or holds the principal, and runs no server-side broadcaster or hot wallet. Gas is sponsored the same way as every other x402 call.
• Amount integrity — amountMicro is validated against the signed authorization value, so the amount you see is the amount that moves.
• Replay-guarded, not idempotent — both authorizations are single-use. Re-submitting a spent deposit authorization is refused with 409 PAYMENT_REPLAY (never double-deposited), and a spent fee authorization with 402 PAYMENT_REPLAY; the original result is not replayed, so keep the X-Deposit-Tx from the first response.

Configuration