ARC Transaction Broadcasting

Broadcast signed BSV transactions using the ARC (Application Runtime & Certificate) protocol via @bsv/sdk.

ARC Overview

ARC is the production-grade transaction broadcaster for BSV. Unlike simple REST broadcast endpoints, ARC:

• Connects to multiple nodes simultaneously (no single point of failure)
• Accepts Extended Format (EF) transactions for script/fee validation
• Returns structured status responses with txStatus
• Supports callback webhooks for confirmation events
• Handles rebroadcast automatically

Two public ARC endpoints are available:

GorillaPool is the default for development. Use TAAL for production if a guaranteed SLA is needed.

Basic Usage

import { Transaction, ARC } from '@bsv/sdk'

// GorillaPool — no API key needed
const result = await tx.broadcast(new ARC('https://arc.gorillapool.io'))

// TAAL — API key required
const result = await tx.broadcast(new ARC('https://api.taal.com/arc', 'mainnet_xxxxxx'))

// Check result
if (result.status === 'success') {
  console.log('txid:', result.txid)
  console.log('status:', result.message) // e.g. "SEEN_ON_NETWORK"
} else {
  console.error('broadcast failed:', result.description)
}

ArcConfig Options

Use ArcConfig for advanced configuration:

import { ARC, ArcConfig } from '@bsv/sdk'

const config: ArcConfig = {
  apiKey: 'mainnet_xxxxxx',          // Optional for GorillaPool
  callbackUrl: 'https://myapp.com/arc-callback',  // Webhook for confirmations
  callbackToken: 'my-secret-token',  // Sent as Authorization header in callbacks
  deploymentId: 'my-app-v1',         // Identifies your app in ARC logs
  headers: { 'X-Custom': 'value' },  // Extra headers on all requests
}

const broadcaster = new ARC('https://arc.gorillapool.io', config)
await tx.broadcast(broadcaster)

Callback Webhook

When callbackUrl is set, ARC will POST to that URL when the transaction is:

• Seen in mempool (SEEN_ON_NETWORK)
• Mined in a block (MINED)
• Double-spent (DOUBLE_SPEND_ATTEMPTED)

The callback body contains { txid, txStatus, blockHash?, blockHeight? }.

Transaction Formats

The ARC broadcaster internally calls tx.toHexEF() (Extended Format). EF includes source transaction data so ARC can validate scripts and fees without looking up inputs separately.

If EF serialization fails (source transactions not attached), it falls back to raw hex.

// Manually build with source tx attached (enables EF)
tx.addInput({
  sourceTXID: '...',
  sourceOutputIndex: 0,
  sourceTransaction: parentTx,  // Attaches parent → enables EF
  unlockingScriptTemplate: new P2PKH().unlock(key),
})

Batch Broadcasting

Broadcast multiple transactions in one call:

const broadcaster = new ARC('https://arc.gorillapool.io')
const results = await broadcaster.broadcastMany([tx1, tx2, tx3])

for (const r of results) {
  console.log(r)
}

broadcastMany posts to /v1/txs (vs /v1/tx for single). Results are mixed — some may succeed while others fail.

Broadcasting a BEEF Transaction

When using WalletClient with noSend: true, the wallet returns a BEEF transaction. To broadcast it via ARC:

import { Transaction, ARC } from '@bsv/sdk'

// Parse BEEF bytes from WalletClient
const tx = Transaction.fromBEEF(beefBytes)

// Or from hex BEEF string
const tx = Transaction.fromHexBEEF(beefHex)

// Broadcast
const result = await tx.broadcast(new ARC('https://arc.gorillapool.io'))

Script Usage

# Broadcast a raw/EF tx hex
bun run skills/broadcast-arc/scripts/broadcast.ts <tx-hex>

# Broadcast BEEF hex
bun run skills/broadcast-arc/scripts/broadcast.ts --beef <beef-hex>

# Use TAAL with API key
bun run skills/broadcast-arc/scripts/broadcast.ts <tx-hex> --key mainnet_xxxxxx --url https://api.taal.com/arc

Error Codes

A 409 response (already known) should be treated as success — the tx is already on the network.

txStatus Values

Related Skills

• wallet-brc100 — create transactions with WalletClient including noSend: true BEEF pattern
• wallet-send-bsv — build and sign transactions with a WIF key before broadcasting
• decode-bsv-transaction — inspect a transaction before or after broadcast