Bitcoin Transactions

Components for building, signing, and broadcasting Bitcoin transactions, plus signature hash computation.

Avoid public RPC endpoints

White Rabbit runs on shared infrastructure with a shared outbound IP pool. Public endpoints enforce rate limits per IP — under load this can cause errors across all workspaces sharing that IP. Use a private or self-hosted Bitcoin node. See Connecting to Bitcoin.

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BROADCAST_BITCOIN_TRANSACTION

BROADCAST_BITCOIN_TRANSACTION Workflow Component

Broadcasts a finalized raw transaction to the Bitcoin network and returns the transaction ID.

Config

Field	Type	Required	Description
network	'mainnet' | 'testnet'	Yes	Target Bitcoin network

Inputs

Field	Type	Description
signedTransaction	string (hex)	Raw transaction hex to broadcast

Outputs

Field	Type	Description
txid	string	Transaction ID (64-char hex)

SDK example

import { WorkspaceClient, ComponentModule } from 'caller-sdk';
const workspace = new WorkspaceClient({ apiKey: process.env.WR_API_KEY! });

const result = await workspace.call(ComponentModule.BROADCAST_BITCOIN_TRANSACTION, {
  signedTransaction: 'deadbeef...',
}).promise();
console.log(result.txid);

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BUILD_BITCOIN_TRANSACTION

BUILD_BITCOIN_TRANSACTION Workflow Component

Builds an unsigned PSBT with UTXO selection, fee estimation, and sighash generation. Supports optional locktime, OP_RETURN data, change address configuration, and fee deduction.

Config

Field	Type	Required	Default	Description
paymentType	'p2pkh' | 'p2sh-p2wpkh' | 'p2wpkh' | 'p2tr'	Yes	—	Bitcoin payment type (address format)
network	'mainnet' | 'testnet'	Yes	—	Target Bitcoin network
deductFee	boolean	No	false	When true, subtracts the estimated fee from amount instead of adding it on top

Inputs

Field	Type	Description
recipientAddress	string	Destination Bitcoin address
amount	number	Amount to send in satoshis (non-negative integer)
publicKey	string (hex)	Sender public key — compressed 33 bytes (66 hex) or uncompressed 65 bytes (130 hex)
locktime	string | null	Transaction locktime as block height string. null to disable
opReturnData	string | null	Hex data to embed in an OP_RETURN output. null to skip
changeAddress	string | null	Address for change output. null uses the sender's address

Outputs

Field	Type	Description
unsignedTransaction	string (hex)	Hex-encoded unsigned PSBT
messageHashes	string[]	Array of sighash hex strings, one per input (each 64 hex chars)
estimatedFee	number	Estimated network fee in satoshis

SDK example

import { WorkspaceClient, ComponentModule } from 'caller-sdk';
const workspace = new WorkspaceClient({ apiKey: process.env.WR_API_KEY! });

const result = await workspace.call(ComponentModule.BUILD_BITCOIN_TRANSACTION, {
  recipientAddress: 'bc1q...',
  amount: 50000,
  publicKey: '02abc123...',
  locktime: null,
  opReturnData: null,
  changeAddress: null,
}).promise();
console.log(result.unsignedTransaction);
console.log(result.messageHashes); // sign each of these
console.log(result.estimatedFee);

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SIGN_BITCOIN_TRANSACTION

SIGN_BITCOIN_TRANSACTION Workflow Component

Applies signatures to an unsigned PSBT and produces a finalized raw transaction ready to broadcast.

Config

None.

Inputs

Field	Type	Description
unsignedTransaction	string (hex)	Hex-encoded PSBT from BUILD_BITCOIN_TRANSACTION
signatures	string[]	Hex-encoded signatures, one per input
publicKey	string (hex)	Signer public key — compressed 33 bytes (66 hex) or uncompressed 65 bytes (130 hex)

Outputs

Field	Type	Description
signedTransaction	string (hex)	Finalized raw transaction hex, ready to broadcast

SDK example

import { WorkspaceClient, ComponentModule } from 'caller-sdk';
const workspace = new WorkspaceClient({ apiKey: process.env.WR_API_KEY! });

const result = await workspace.call(ComponentModule.SIGN_BITCOIN_TRANSACTION, {
  unsignedTransaction: buildResult.unsignedTransaction,
  signatures: ['3045...', '3044...'],
  publicKey: '02abc123...',
}).promise();
console.log(result.signedTransaction);

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COMPUTE_BITCOIN_SIGNATURE_HASH

COMPUTE_BITCOIN_SIGNATURE_HASH Workflow Component

Computes a signature hash for a message using either the standard Bitcoin message format or raw SHA-256 hashing.

Config

Field	Type	Required	Description
format	'bitcoin-message' | 'raw'	Yes	bitcoin-message produces a standard signed-message hash. raw produces a double SHA-256 hash

Inputs

Field	Type	Description
message	string	Message string to hash

Outputs

Field	Type	Description
messageHash	string	32-byte hash as 64-char hex, ready for external signing

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Transaction flow

GET_BITCOIN_DERIVATION_PATH
         │
         ▼
  (external signing)
  → public key
         │
         ▼
BUILD_BITCOIN_TRANSACTION ─── messageHashes ──▶ (external signing)
         │                                              │ signatures
         │                                              ▼
         └─── unsignedTransaction ──▶ SIGN_BITCOIN_TRANSACTION
                                               │
                                               ▼ signedTransaction
                                   BROADCAST_BITCOIN_TRANSACTION

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Stage statuses

Status	Meaning
CREATED	Queued, waiting to execute
RUNNING	Actively executing
COMPLETED	Finished successfully
FAILED	Failed — check error field