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name: bitcoin-libraries-mempool-js description: | mempool.js (@mempool/mempool.js): TypeScript client for mempool.space API. REST + WebSocket; address history, fee estimates, mining stats. USE WHEN: integrating mempool.space data, building wallets / explorers. allowed-tools: Read, Grep, Glob

mempool.js

Official mempool.space API client.

Repo: github.com/mempool/mempool.js.

Install

npm install @mempool/mempool.js

Quick examples

import mempoolJS from "@mempool/mempool.js";

const { bitcoin: { addresses, fees, transactions, blocks, mempool } } =
    mempoolJS({ hostname: "mempool.space" });

// Fees
const recommended = await fees.getFeesRecommended();
// { fastestFee, halfHourFee, hourFee, economyFee, minimumFee }

// Address
const utxos = await addresses.getAddressTxsUtxo({ address: "bc1q..." });
const txs = await addresses.getAddressTxs({ address: "bc1q..." });

// Tx
const tx = await transactions.getTx({ txid: "abc..." });
const status = await transactions.getTxStatus({ txid: "abc..." });

// Mempool
const blocksProj = await mempool.getMempoolBlocks();

WebSocket

const ws = await mempoolJS.ws({ hostname: "mempool.space" });
ws.on("blocks", (block) => console.log("New block:", block.id));
ws.on("mempool-blocks", (mbs) => console.log("Projection:", mbs));
ws.send({ action: "want", data: ["blocks", "mempool-blocks"] });

Use cases

• Web wallet fee selection.
• Block explorer integrations.
• Fee tracker apps.

Self-hosted

Same API works against your own mempool.space instance:

mempoolJS({ hostname: "your-mempool.local" });

See also

• ../../infrastructure/mempool-space/SKILL.md
• bitcoinjs-lib/SKILL.md
• scure-btc-signer/SKILL.md