Bitcoin Wallet SDK Comparison

How to Choose a Bitcoin Wallet SDK

Selecting the right Bitcoin wallet SDK is one of the most important decisions when building a Bitcoin application. The SDK you choose affects your development speed, security posture, and the features available to your users.

Key factors to consider include your team's programming language expertise, whether you need Lightning Network support, the level of abstraction you want, and the maturity of the library's ecosystem.

SDK by Programming Language

Here's a quick guide based on your primary development language:

• Rust: use BDK for wallets or rust-bitcoin for low-level primitives. For Lightning, use LDK.
• JavaScript/TypeScript: bitcoinjs-lib is the standard choice. BDK also offers WASM bindings for web apps.
• Swift/Kotlin (Mobile): both BDK and LDK provide native mobile bindings with excellent documentation.
• Python: python-bitcoinlib works well for scripts and prototyping. BDK has Python bindings for production use.
• C#/.NET: NBitcoin is the most comprehensive option with years of production use.

BDK vs bitcoinjs-lib

This is the most common comparison developers make. Here's the key difference:

BDK is a higher-level wallet library. It handles wallet state, coin selection, syncing with the blockchain, and descriptor-based accounts out of the box. It's ideal if you want to build a full wallet application quickly.

bitcoinjs-lib is lower-level. It gives you tools to build and sign transactions, but you manage wallet state yourself. It's better for applications that need fine-grained control or already have their own wallet infrastructure.

Lightning Network SDKs

If your application needs instant, low-fee payments, you'll want Lightning support. The Lightning Dev Kit (LDK) is the most flexible option: it lets you embed Lightning into any application without running a full node.

For simpler integrations, consider APIs like Spark that abstract away Lightning complexity while still giving users self-custody.

Frequently Asked Questions

Which Bitcoin SDK should I use for a mobile wallet?

For mobile wallets, BDK is the top choice. It has native bindings for both Swift (iOS) and Kotlin (Android), with excellent documentation and active maintenance. The library handles complex wallet operations like coin selection and UTXO management automatically.

What is the best JavaScript Bitcoin library?

bitcoinjs-lib is the most widely used JavaScript Bitcoin library. It's battle-tested, well-documented, and supports all major Bitcoin features including PSBT, SegWit, and Taproot. For web applications, BDK's WASM bindings are also worth considering.

Is BDK production-ready?

Yes. BDK is used in production by multiple companies including Mutiny Wallet, Foundation Devices, and Bull Bitcoin. It's backed by Spiral (a Block company) and has an active development team and community.

What is the difference between BDK and LDK?

BDK (Bitcoin Dev Kit) is for on-chain Bitcoin wallets. LDK (Lightning Dev Kit) is for Lightning Network functionality. They're separate libraries that can be used together: use BDK for your on-chain wallet and LDK for Lightning channels.

Can I build a custodial wallet with these SDKs?

Technically yes, but all these SDKs are designed for self-custody applications. They manage private keys locally. If you're building a custodial service, you'll need additional infrastructure for key management and security.

Which SDK supports Taproot?

All major SDKs now support Taproot (BIP 340, 341, 342). BDK, bitcoinjs-lib, rust-bitcoin, and NBitcoin all have Taproot support. Check each library's documentation for the minimum version required.

What are output descriptors and why do they matter?

Output descriptors are a standard way to describe how Bitcoin addresses are derived. BDK uses descriptors as its primary wallet model, making it easy to import/export wallets and support complex setups like multisig. If you need advanced wallet features, descriptor support is important.

How do I sync wallet state with the blockchain?

BDK provides built-in blockchain sync using Electrum servers, Esplora APIs, or Bitcoin Core RPC. With bitcoinjs-lib, you need to implement syncing yourself using a service like mempool.space or your own Electrum server.

Which SDK is best for building a Bitcoin exchange?

For exchange infrastructure, NBitcoin (C#) and rust-bitcoin are popular choices due to their low-level control and production track record. You'll likely need to combine an SDK with hot/cold wallet infrastructure and HSM integration.

Are these SDKs free to use?

Yes, all SDKs listed here are open-source and free to use. Most use permissive licenses like MIT or Apache 2.0. Always check the specific license in each repository for commercial use requirements.