Sign & Broadcast

Signs an unsigned transaction with the provided private key and broadcasts it to Base mainnet. Returns the transaction hash and Basescan link.

Endpoint

POST https://pinionos.com/skill/broadcast

Price: $0.01 USDC per call (x402 on Base)

Request Body

{
  "tx": {
    "to": "0x7a21...",
    "value": "0xb1a2bc2ec50000",
    "data": "0x",
    "chainId": 8453
  },
  "privateKey": "0x4b3f..."
}

Field	Type	Required	Description
tx	object	yes	Unsigned transaction object (from /send or /trade skills)
tx.to	string	yes	Recipient or contract address
tx.value	string	no	ETH value in hex (default: "0x0")
tx.data	string	no	Calldata in hex (default: "0x")
tx.chainId	number	yes	Must be 8453 (Base mainnet)
privateKey	string	yes	Sender's private key (0x + 64 hex chars)

Example Request

curl -X POST https://pinionos.com/skill/broadcast \
  -H "Content-Type: application/json" \
  -d '{
    "tx": {
      "to": "0x7a21...",
      "value": "0xb1a2bc2ec50000",
      "data": "0x",
      "chainId": 8453
    },
    "privateKey": "0x4b3f..."
  }'

The first request returns HTTP 402 with payment requirements. Sign a USDC TransferWithAuthorization (EIP-3009) and retry with the X-PAYMENT header.

Example Response

{
  "txHash": "0xabc123...",
  "explorerUrl": "https://basescan.org/tx/0xabc123...",
  "from": "0x1234...",
  "to": "0x7a21...",
  "network": "base",
  "status": "submitted",
  "note": "Transaction submitted to Base. It may take a few seconds to confirm.",
  "timestamp": "2026-02-17T12:00:00.000Z"
}

When to Use

• After calling /send to transfer ETH or USDC -- pass the returned tx object here with the sender's private key to execute it.
• After calling /trade to swap tokens -- broadcast the approve tx first (if present), wait for confirmation, then broadcast the swap tx.
• Any time you have an unsigned Base transaction and need to sign + broadcast it.

Typical Flow

1. Call /send or /trade to get an unsigned transaction.
2. Ask the user for their private key.
3. Call /broadcast with the unsigned tx and the private key.
4. Return the tx hash and Basescan link to the user.

Security

• The private key is sent over HTTPS and used only to sign the transaction. It is not stored or logged.
• Only use this with wallets you control and amounts you're comfortable with.
• The sender's wallet needs ETH on Base for gas fees.