bitcoinjs-lib

The classic JS/TS library for Bitcoin. Browser + Node compatible.

Repo: github.com/bitcoinjs/bitcoinjs-lib.

Install

npm install bitcoinjs-lib ecpair tiny-secp256k1

As of 15 September 2026 the npm latest tag is 7.0.2 (published 2026-09-07); the newest git tag and CHANGELOG entry is 7.0.1 (January 2026), so 7.0.2 is an npm-only patch with no release notes. The v6 line is still published under the maintenance-v6 dist-tag (6.1.8, 2026-09-07) and v5 under maintenance-v5 (5.2.1). Examples below target 7.x, which requires Node >= 18.

Quick examples

Address generation

import * as bitcoin from "bitcoinjs-lib";
import ECPairFactory from "ecpair";
import * as ecc from "tiny-secp256k1";

const ECPair = ECPairFactory(ecc);
const network = bitcoin.networks.bitcoin;
const keyPair = ECPair.makeRandom({ network });
const { address } = bitcoin.payments.p2wpkh({
    pubkey: keyPair.publicKey, network   // Uint8Array in 7.x
});

Tx construction (modern: psbt)

const psbt = new bitcoin.Psbt({ network });
psbt.addInput({
    hash: "txid...",
    index: 0,
    witnessUtxo: { script: spk, value: 100000n }   // bigint in 7.x
});
psbt.addOutput({ address: dest, value: 99000n });
psbt.signInput(0, keyPair);
psbt.finalizeAllInputs();
const tx = psbt.extractTransaction();
console.log(tx.toHex());

BIP32

import { BIP32Factory } from "bip32";
import * as ecc from "tiny-secp256k1";

const bip32 = BIP32Factory(ecc);
const root = bip32.fromSeed(seedBytes);
const child = root.derivePath("m/84'/0'/0'/0/0");

v6 -> v7 breaking changes

From the 7.0.0 CHANGELOG entry (7.0.0 published to npm 2025-10-02):

• Buffer -> Uint8Array. Every public API returns Uint8Array (payments, Transaction, Psbt, Block, script). Buffer is still accepted as input, because it subclasses Uint8Array.
• Satoshi values are bigint. Transaction.Output.value, PSBT output values, witnessUtxo.value and Psbt.getFee(). Migration per the changelog: value: 10000 becomes BigInt(10000) or 10000n.
• typeforce -> valibot. All typeforce re-exports were removed (Satoshi, BufferN, UInt32, Hex, ...); valibot *Schema exports replace them.
• Dual CJS/ESM. "type": "module", an exports map, .cjs files for the CJS build, and .js extensions required on internal import paths.
• Node >= 18 (was 8).
• Dependency majors: bip174 2.x -> 3.x, bs58check 3.x -> 4.x, varuint-bitcoin 1.x -> 2.x; valibot and uint8array-tools added.

Staying on v6 is still viable via the maintenance-v6 dist-tag, but new code should target 7.x.

Companion packages

• bip32 — HD derivation.
• ecpair — ECPair signer; split out of the main package in v6.
• bip39 — mnemonic.
• bip174 — PSBT wire codec. Still an external runtime dependency of 7.x (^3.0.0, latest 3.0.1 September 2026); only the user-facing Psbt class lives in bitcoinjs-lib, and it wraps a PsbtBase instance from this package, exposed as psbt.data.
• tiny-secp256k1 — secp256k1 ops.
• bolt11 — BOLT11 invoice decode.

Network constants

bitcoinjs.networks:

• bitcoin (mainnet).
• testnet.
• regtest.

Compared

@scure/btc-signer audit history as of September 2026: cure53 audited v0.3.0 in February 2023, when the package was still named micro-btc-signer (report: https://cure53.de/audit-report_micro-btc-signer.pdf); v2.2.0 was self-audited by the maintainer in April 2026. MuSig2 and UTXO selection are documented as not yet audited.

Use cases

• Web wallets, browser extensions.
• Node.js Bitcoin services.
• React Native apps (with polyfills).

Common pitfalls

• bitcoin.ECPair was removed in 6.0.0, not merely deprecated. Install the separate ecpair package and build it with ECPairFactory(ecc), or use bip32. tiny-secp256k1 is the ECC backend you pass into those factories, not a drop-in replacement for the keypair type.
• Mixing number and bigint amounts under 7.x: adding an output with a number value throws Error adding output.. Every satoshi amount must be a bigint.
• Browser bundlers (Webpack 5+, Vite): 7.x imports no crypto or buffer node builtin and returns Uint8Array from every public API, so a Buffer polyfill is only needed for your own code that still hands Buffers in. v6 commonly needed both shims.
• Network mismatch errors when switching mainnet/testnet.

See also

• scure-btc-signer/SKILL.md
• bcoin-js/SKILL.md
• bolt11-decoder/SKILL.md