Nexus for ICP: A Decentralized Bitcoin Liquidity Management Service

Developers Showcase
1

Project Introduction

Nexus for ICP is a decentralized, self-custodial Bitcoin liquidity management service built entirely on Internet Computer smart contracts. It provides a standardized gateway for developers to plug into the Nexus liquidity market.

Our mission is to provide the underlying Bitcoin transaction primitives for wallets, DEX aggregators, and DeFi protocols within the ICP ecosystem. This library serves not only as the standard interface for interacting with the Nexus protocol but is also engineered to be the core engine for future Decentralized Liquidity Pools (DLPs) and Native BTC Yield products.

By encapsulating complex UTXO management, PSBT (Partially Signed Bitcoin Transaction) orchestration, and Chain Fusion logic, Nexus allows developers to rapidly integrate non-custodial trading for Native BTC and Runes assets via standardized Canister interfaces, eliminating the need to build low-level Bitcoin infrastructure from scratch.

Overview

Core Features & Technical Highlights:

  • Non-Custodial Settlement Mechanism: leveraging Threshold ECDSA technology, we implement fully decentralized signing logic, ensuring that control over funds always remains with the user.

  • Liquidity & Yield Engine: Provides standardized interfaces for liquidity injection and withdrawal, supporting the creation of AMM (Automated Market Maker) yield models based on native BTC.

  • Automated PSBT Orchestration: The Nexus Node module automatically handles input/output construction and multi-party signing workflows, supporting complex transaction structures.

  • Production-Grade Stability: The core settlement engine utilizes a battle-tested architecture, ensuring high availability and secure fund handling in a mainnet environment.

  • Native Asset Support: Full support for Bitcoin mainnet assets, including Native BTC and the Runes Protocol, without bridges or wrapped tokens.

  • Off-Chain Verification: Built-in Merkle Proof Server logic accelerates the confirmation of Bitcoin transaction states on the ICP chain.

Bitcoin-Native Intent Execution & Liquidity Protocol

The Nexus framework operates by relying on the Nexus Composer Server and the Merkle Proof Server.

The protocol’s architectural innovation lies in its pure Bitcoin-native approach, utilizing UTXOs, multi-sig schemes, and PSBTs to achieve complex financial operations without introducing additional trust assumptions. This design preserves Bitcoin’s consensus-driven security model while unlocking advanced functionalities like atomic multi-party swaps, concentrated liquidity provision, and intent-based transaction coordination.

At the heart of the design is Intent-Based Execution. Users do not need to specify the exact transaction path; they simply define their desired outcome. The Nexus Composer processes these intents and coordinates with the Nexus Node network to find the optimal execution across multiple liquidity sources.

Users can operate their own Nexus nodes in a self-custodial manner or host them on self-managed instances (e.g., via dot-swap-liquid). This allows liquidity providers to earn yield from Bitcoin market volatility without sacrificing self-custody security or trustlessness.

Usage Examples

  1. Installation Nexus operates as Canister smart contracts. Developers can integrate the core Nexus Canister into local development environments or mainnet projects via the DFINITY SDK (dfx).

  2. Integration Declare the Nexus Canister dependency in your project’s dfx.json. The specific Wasm binaries and Candid interface definitions (.did) are available on our GitHub release page.

  3. How to Execute a Swap via Nexus The workflow consists of four steps:

  • Submit Intent: The client submits a transaction request containing the trading pair and amount.

  • Lock UTXO: The system verifies and locks the corresponding UTXO.

  • Fetch PSBT: The client retrieves the unsigned PSBT data.

  • Sign & Broadcast: The user signs locally and returns the signature data. Nexus then completes the assembly and broadcasts it to the Bitcoin mainnet via the bitcoin-canister.

For detailed Rust and Motoko examples and API definitions, please refer to the examples directory in our GitHub repository.

Everything About Nexus for ICP

Documentation

We provide comprehensive technical documentation, including architectural deep dives, API references, and integration guides for wallets and DEXs.

Protocol License

Nexus for ICP is released under an open-source license.

  • [MIT LICENSE]

Resources

Roadmap

Phase 1 (Completed): The Bitcoin-native Nexus protocol has been systematically advanced in three stages:

  1. AMM Core: Implemented CPMM logic, liquidity pool deposit/withdrawal, and accounting on ICP Testnet.

  2. Intent Model: Built the intent verification system and pricing curve rules, simulating the full flow of intent matching and rejection.

  3. On-Chain Integration: Achieved light node verification by connecting with Omnity to verify Bitcoin transaction states and SPV proofs, executing intent adjudication based on on-chain finality with a complete audit trail.

Phase 2 (In Development): State Channels for High-Frequency Trading: We are developing an extension layer based on State Channels. This phase aims to combine off-chain matching with on-chain settlement to significantly reduce transaction latency and gas costs, providing high-performance support for professional trading applications.

1 Like
2

Is there an audit planned or already done?