getmempoolentry - Bitcoin

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

This method returns mempool data for a specific transaction that is currently in the memory pool.

Parameters

Parameter	Type	Required	Description
txid	string	Yes	The transaction ID

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": "getmempoolentry",
    "params": ["4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"],
    "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: 'getmempoolentry',
    params: ["4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"],
    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': 'getmempoolentry',
        'params': ["4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"],
        '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": "getmempoolentry",
            "params": ["4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;

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

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": {
        "vsize": 141,
        "weight": 561,
        "time": 1706886100,
        "height": 830000,
        "descendantcount": 1,
        "descendantsize": 141,
        "ancestorcount": 1,
        "ancestorsize": 141,
        "fees": {
            "base": 2.82e-05,
            "modified": 2.82e-05,
            "ancestor": 2.82e-05,
            "descendant": 2.82e-05
        },
        "depends": [],
        "spentby": [],
        "bip125-replaceable": true,
        "unbroadcast": false
    }
}

Response Parameters

Parameter	Type	Description
jsonrpc	string	JSON-RPC protocol version ("2.0")
id	string	Request identifier matching the request
result	object	Mempool entry object

Result Object

Field	Type	Description
vsize	number	Virtual transaction size
fees.base	number	Base fee in BTC
ancestorcount	number	Number of in-mempool ancestor transactions
descendantcount	number	Number of in-mempool descendant transactions
bip125-replaceable	boolean	Whether the transaction signals RBF

Use Cases

• Fee Analysis: Read a pending transaction's fee and size

• RBF Detection: Check whether a transaction is replaceable

• CPFP Planning: Read ancestor and descendant relationships

• Monitoring: Track a specific pending transaction

Error Handling

Error Code	Message	Description
403	Forbidden	Missing or invalid ACCESS-TOKEN
-5	Not found	The requested block or transaction was not found
-8	Invalid parameter	A parameter is out of range or malformed
-32602	Invalid params	A parameter is missing or has the wrong type