wasm-utxo

This project is the successor of the Javascript utxo-lib package.

It provides WASM bindings for the rust-bitcoin and rust-miniscript crates that help verify and co-sign transactions built by the BitGo Wallet Platform API.

Documentation

• src/wasm-bindgen.md - Guide for creating WASM bindings using the namespace pattern
• js/README.md - TypeScript wrapper layer architecture and best practices
• cli/README.md - Command-line interface for address and PSBT operations

Status

This project is under active development.

| Feature | Bitcoin | BitcoinCash | BitcoinGold | Dash | Doge | Litecoin | Zcash | | --------------------------------------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | | Descriptor Wallet: Address Support | ✅ Complete | 🚫 | 🚫 | 🚫 | 🚫 | 🚫 | 🚫 | | Descriptor Wallet: Transaction Support | ✅ Complete | 🚫 | 🚫 | 🚫 | 🚫 | 🚫 | 🚫 | | FixedScript Wallet: Address Generation | ✅ Complete | ✅ Complete | ✅ Complete | ✅ Complete | ✅ Complete | ✅ Complete | ✅ Complete | | FixedScript Wallet: Transaction Support | ✅ Complete | ✅ Complete | ✅ Complete | ✅ Complete | ✅ Complete | ✅ Complete | ✅ Complete |

Zcash Features

Zcash support includes:

• Network Upgrade Awareness: Automatic consensus branch ID determination based on block height
• All Network Upgrades: Support for Overwinter, Sapling, Blossom, Heartwood, Canopy, Nu5, Nu6, and Nu6_1
• Height-Based API: Preferred createEmpty() method automatically selects correct consensus rules
• Parity Testing: Validated against zebra-chain for accuracy across all network upgrades

Inspect Feature

The inspect feature adds PSBT and transaction parsing into hierarchical node trees, useful for building tree-view UIs and CLI formatters.

It is behind a Cargo feature flag because it pulls in extra dependencies (serde, serde_json, num-bigint, hex) that are not needed for core wallet operations.

Rust

// Cargo.toml
wasm-utxo = { path = ".", features = ["inspect"] }

// Usage
use wasm_utxo::inspect::{parse_psbt_bytes_with_network, parse_tx_bytes_with_network, Node};

TypeScript

Available as a separate import path, not included in the main @bitgo/wasm-utxo entry:

import { parsePsbtToNode, parseTxToNode, isInspectEnabled } from "@bitgo/wasm-utxo/inspect";

The published npm package includes stub implementations that return isInspectEnabled() === false and throw runtime errors from the parse functions. To get a working build, compile the WASM with --features inspect (see packages/webui/scripts/build-wasm.sh).

Building

Mac

Requires Homebrew LLVM (Apple's Clang doesn't support WASM targets):

brew install llvm
npm run build

Docker (optional)

If you prefer a containerized build environment:

make -f Container.mk build-image
make -f Container.mk build-wasm