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:

Provider	URL	API Key Required
GorillaPool	https://arc.gorillapool.io	No (mainnet, public beta)
TAAL	https://api.taal.com/arc	Yes — get from console.taal.com

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

Code	Meaning
200	Success — transaction accepted
409	Already known — txid exists (not an error)
422	Invalid transaction — script/fee error
465	Cumulative fee too low
473	Double spend detected

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

txStatus Values

Status	Meaning
STORED	Received, not yet validated
ANNOUNCED_TO_NETWORK	Propagated to nodes
SEEN_ON_NETWORK	Seen by multiple nodes
MINED	Included in a block
SEEN_IN_ORPHAN_MEMPOOL	In an orphan branch
DOUBLE_SPEND_ATTEMPTED	Competing transaction detected

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