bitcoinj

Java/Kotlin Bitcoin library. Long-standing (since 2011). Used in many JVM-based wallets.

Repo: github.com/bitcoinj/bitcoinj.

Current release: 0.17.1 (4 May 2026). Prior: 0.17 (21 February 2025), 0.16.5 (27 January 2025).

Install

Maven:

<dependency>
    <groupId>org.bitcoinj</groupId>
    <artifactId>bitcoinj-core</artifactId>
    <version>0.17.1</version>
</dependency>

Gradle:

implementation 'org.bitcoinj:bitcoinj-core:0.17.1'

Do not ship 0.16.x or 0.15.x. 0.17.1 fixes two verification bypasses in ScriptExecution.correctlySpends() — GHSA-hfcf-v2f8-x9pc / CVE-2026-44714, CVSS 7.5, disclosed 4 May 2026. The P2PKH and native P2WPKH fast paths verify an attacker-supplied signature against an attacker-supplied pubkey without checking that pubkey against the hash committed in the scriptPubKey, so any keypair satisfies local verification of arbitrary P2PKH/P2WPKH outputs. Affected: 0.15.x, 0.16.x and 0.17; patched only in 0.17.1 — there is no 0.16.x backport (as of September 2026). Pure SPV never verifies input signatures and is untouched, but anything calling correctlySpends() must upgrade. 0.17.1 also lowers the default fee to 10000 sat/vkB.

Quick example

0.17 API (Network/BitcoinNetwork in place of NetworkParameters):

import org.bitcoinj.base.Address;
import org.bitcoinj.base.BitcoinNetwork;
import org.bitcoinj.base.ScriptType;
import org.bitcoinj.core.PeerGroup;
import org.bitcoinj.net.discovery.DnsDiscovery;
import org.bitcoinj.wallet.Wallet;

Wallet wallet = Wallet.createDeterministic(BitcoinNetwork.MAINNET, ScriptType.P2WPKH);

Address addr = wallet.currentReceiveAddress();
System.out.println(addr.toString());

// Sync via SPV (BIP37 bloom filters — see pitfalls)
PeerGroup peerGroup = new PeerGroup(BitcoinNetwork.MAINNET, blockChain);
peerGroup.addPeerDiscovery(new DnsDiscovery(BitcoinNetwork.MAINNET));
peerGroup.start();
peerGroup.downloadBlockChain();

Parse a user-supplied address with wallet.parseAddress(str) or AddressParser.getDefault(network); the static Address.fromString(params, str) is deprecated in 0.17.

Migrating 0.16 -> 0.17

0.17 is a large breaking release. Per its release notes:

• NetworkParameters aspects extracted to a Network interface and BitcoinNetwork enum; "prod"/"prodnet" is now BitcoinNetwork.MAINNET.
• New AddressParser replaces the static Address.fromString() constructors.
• All Guava ListenableFuture usage migrated to CompletableFuture (transitional ListenableCompletableFuture implements both; the Guava form goes away after 0.17).
• New packages org.bitcoinj.base (fundamental types, no Guava — becomes its own module in 0.18) and org.bitcoinj.crypto (no direct BouncyCastle in the crypto API; AesKey replaces BC KeyParameter).
• Script.ScriptType is now org.bitcoinj.base.ScriptType; Coin and Address moved from org.bitcoinj.core to org.bitcoinj.base.
• Removed: all database-backed block stores, HttpDiscovery (use DnsDiscovery or a hardcoded seed node), GetUTXOsMessage/UTXOsMessage, Serializable/Cloneable, married key chains, the basic -> deterministic keychain upgrade path.
• Requirements rise: JDK 11+ to build; Java 11 for every module except bitcoinj-core (still Java 8); Android API level 26 (Android 8.0) for bitcoinj-core.

Features

• HD wallet (BIP32/39/44).
• SPV / BIP37 (deprecated bloom filter SPV). No BIP157/158 client; Services.NODE_COMPACT_FILTERS is only a service-bit constant.
• Tx construction + signing.
• Network discovery.
• Coin selection.

Compared

Taproot detail: ScriptType.P2TR exists and ScriptPattern/SegwitAddress handle P2TR outputs, so you can pay a bc1p... address. But DeterministicKeyChain still rejects any outputScriptType other than P2PKH or P2WPKH and there is no Schnorr signing, so a bitcoinj wallet cannot receive to or spend from P2TR — verified against the v0.17.1 source in September 2026. The 0.16 release notes ("send to P2TR addresses; receiving and spending ... in a future release") still describe 0.17.1.

For new projects, bdk-jvm is generally recommended. bitcoinj has better adoption for legacy / Android-native cases.

Use cases

• Android wallets (legacy).
• JVM backend services.
• Educational — readable Java code.

Common pitfalls

• BIP37 SPV is insecure for privacy (filter-based deanon).
• Slower to adopt new BIPs (Taproot receive/spend still missing as of 0.17.1, September 2026).
• Memory-heavy: not great for resource-constrained Android.

See also

• bdk-jvm/SKILL.md
• ../../wallets/hd/SKILL.md