joinpsbts - Bitcoin

Example code for the joinpsbts JSON-RPC method. Complete guide on how to use joinpsbts JSON-RPC in GetBlock Web3 documentation.

This method joins multiple distinct PSBTs into a single PSBT by concatenating their inputs and outputs. The PSBTs must not share inputs.

Parameters

Parameter	Type	Required	Description
txs	array	Yes	The base64-encoded PSBTs to join

Request

cURL

curl --location --request POST 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "joinpsbts",
    "params": [["cHNidP8BAHUCAAAAASaBcTce3/KF6Tet7qSze3gADAVmy7OtZGQXE8pCFxv2AAAAAAD+////AtPf9QUAAAAAGXapFPUKlXhpm/rZ4JBKZ2n3nQ4jCMYBiKz1AAAAAA==", "cHNidP8BAHUCAAAAASaBcTce3/KF6Tet7qSze3gADAVmy7OtZGQXE8pCFxv2AAAAAAD+////AtPf9QUAAAAAGXapFPUKlXhpm/rZ4JBKZ2n3nQ4jCMYBiKz1AAAAAA=="]],
    "id": "getblock.io"
}'

bitcoinjs-lib

example.js

const axios = require('axios');

const response = await axios.post('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/', {
    jsonrpc: '2.0',
    method: 'joinpsbts',
    params: [["cHNidP8BAHUCAAAAASaBcTce3/KF6Tet7qSze3gADAVmy7OtZGQXE8pCFxv2AAAAAAD+////AtPf9QUAAAAAGXapFPUKlXhpm/rZ4JBKZ2n3nQ4jCMYBiKz1AAAAAA==", "cHNidP8BAHUCAAAAASaBcTce3/KF6Tet7qSze3gADAVmy7OtZGQXE8pCFxv2AAAAAAD+////AtPf9QUAAAAAGXapFPUKlXhpm/rZ4JBKZ2n3nQ4jCMYBiKz1AAAAAA=="]],
    id: 'getblock.io'
}, {
    headers: { 'Content-Type': 'application/json' }
});

console.log(response.data.result);

Request

example.py

import requests

response = requests.post(
    'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'joinpsbts',
        'params': [["cHNidP8BAHUCAAAAASaBcTce3/KF6Tet7qSze3gADAVmy7OtZGQXE8pCFxv2AAAAAAD+////AtPf9QUAAAAAGXapFPUKlXhpm/rZ4JBKZ2n3nQ4jCMYBiKz1AAAAAA==", "cHNidP8BAHUCAAAAASaBcTce3/KF6Tet7qSze3gADAVmy7OtZGQXE8pCFxv2AAAAAAD+////AtPf9QUAAAAAGXapFPUKlXhpm/rZ4JBKZ2n3nQ4jCMYBiKz1AAAAAA=="]],
        'id': 'getblock.io'
    }
)

print(response.json())

Rust

example.rs

use reqwest::Client;
use serde_json::{json, Value};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();

    let response = client
        .post("https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&json!({
            "jsonrpc": "2.0",
            "method": "joinpsbts",
            "params": [["cHNidP8BAHUCAAAAASaBcTce3/KF6Tet7qSze3gADAVmy7OtZGQXE8pCFxv2AAAAAAD+////AtPf9QUAAAAAGXapFPUKlXhpm/rZ4JBKZ2n3nQ4jCMYBiKz1AAAAAA==", "cHNidP8BAHUCAAAAASaBcTce3/KF6Tet7qSze3gADAVmy7OtZGQXE8pCFxv2AAAAAAD+////AtPf9QUAAAAAGXapFPUKlXhpm/rZ4JBKZ2n3nQ4jCMYBiKz1AAAAAA=="]],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;

    println!("Result: {}", response["result"]);
    Ok(())
}

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "cHNidP8BAHUCAAAAASaBcTce3/KF6Tet7qSze3gADAVmy7OtZGQXE8pCFxv2AAAAAAD+////AtPf9QUAAAAAGXapFPUKlXhpm/rZ4JBKZ2n3nQ4jCMYBiKz1AAAAAA=="
}

Response Parameters

Parameter	Type	Description
jsonrpc	string	JSON-RPC protocol version ("2.0")
id	string	Request identifier matching the request
result	string	The joined base64-encoded PSBT

Use Cases

• Coinjoin: Combine inputs and outputs from multiple parties

• Payment Batching: Merge separate PSBTs into one transaction

• Collaboration: Assemble a shared transaction

• Privacy Tools: Build joined transactions

Error Handling

Error Code	Message	Description
403	Forbidden	Missing or invalid ACCESS-TOKEN
-22	Decode failed	The transaction or script could not be decoded
-8	Invalid parameter	A parameter is out of range or malformed
-32602	Invalid params	A parameter is missing or has the wrong type