8 Bitcoin L2s

Forward the Original Title：Bankless: 8 Bitcoin L2s You Should Pay Attention To

With Bitcoin hitting new all-time highs, it’s time to delve into one of the investment narratives contributing to reigniting interest in the asset: Bitcoin L2.

Bitcoin is the oldest blockchain and, arguably, the most battle-tested cryptocurrency. But is that also its biggest drawback? Transactions are slow and expensive, especially during periods of high trading activity. The Lightning Network is one such payment channel protocol in the Bitcoin scalability scene, a serious and interesting effort, yet it has yet to gain ground-breaking appeal due to issues with user experience and liquidity.

However, the arrival of Ordinal NFTs in January 2023 sparked a massive resurgence of interest in Bitcoin building. This led to a revival of existing scaling efforts like Stacks and a boom in new endeavors adopting various methods. Therefore, one of the next major frontiers in cryptocurrency is the newly revived Bitcoin Layer 2 scene, so let us take you through some emerging contenders aimed at enhancing Bitcoin’s capabilities.

Bison Network

Bison Network, developed by Bison Labs, is a zk-rollup solution using ZK-STARK technology. It aims to significantly increase transaction throughput, reduce costs, and integrate smart contract capabilities around BTC.

By utilizing Ordinals for data storage, Bison ensures that all transactions and smart contracts are as secure and immutable as the underlying Bitcoin blockchain. Its infrastructure includes Bison OS for managing transactions and token contracts and Bison Prover for generating zero-knowledge proofs.

This setup paves the way for more Bitcoin DeFi experiments and allows users to independently verify transactions quickly and efficiently.

Stacks

Stacks stands out in the Bitcoin L2 scene for its unique approach to extending Bitcoin’s functionality, primarily by integrating smart contracts directly on top of Bitcoin. It employs a unique consensus mechanism called Proof of Transfer (PoX), fundamentally linking its operation and security directly to Bitcoin.

A key feature that sets Stacks apart is how users can earn BTC by staking STX tokens. This method not only incentivizes participation in the Stacks ecosystem but also strengthens the bridge between Stacks and Bitcoin, enhancing the value proposition of both networks.

An upcoming Satoshi upgrade will transform Stacks into a proper L2 by fully inheriting Bitcoin’s security. This upgrade will also introduce faster block generation times on Stacks, independent of Bitcoin’s block time, while still achieving 100% Bitcoin finality. This means that once a transaction is confirmed on Stacks, it will inherit the same level of irreversibility as Bitcoin transactions.

BitVM

BitVM introduces a new method for Bitcoin smart contracts without altering the existing rules of Bitcoin. The system allows for verification rather than execution of computations on Bitcoin, similar to the concept of optimistic rollups on Ethereum.

At its core, BitVM utilizes unique hash locks, time locks, and a large taproot system to perform general-purpose computations. This design enables offline execution of programs with minimal on-chain footprint, requiring on-chain operations only in case of disputes.

While BitVM is still in its early stages, its potential to implement advanced features such as Bitcoin sidechain bidirectional hooks and Rollup suggests it is a promising approach to scaling OG blockchain functionality without the need for a soft fork.

Botanix

Botanix Labs pioneered the Spiderchain design, a novel L2 format that allows seamless bidirectional hooks to Bitcoin without altering the Bitcoin base layer. The ongoing Botanix protocol is the first implementation of this novel approach and integrates with the Ethereum Virtual Machine (EVM) to bridge the gap between Bitcoin’s robustness and Ethereum’s multifunctional smart contract ecosystem.

At the core of the Spiderchain design is a coordinator network managing multiset wallets, facilitating the transfer in and out processes between Bitcoin and the Spiderchain. These coordinators run both Bitcoin nodes and Spiderchain nodes and are randomly selected based on Bitcoin block hashes to ensure fair and secure operations.

Chainway

Chainway is another rising force in the Bitcoin L2 space, backed by prominent venture capital firms like Galaxy Digital and Delphi Ventures. The team released the BitcoinDA data availability adapter for connecting Rollups to Bitcoin, and they have also initiated work on Citrea, a zk-rollup solution that uses BitVM to write its proofs into Bitcoin.

Citrea is designed as a “Type 2 zkEVM” for Bitcoin, using zero-knowledge proofs for batch transactions and ensuring validity through succinct proofs. This approach allows anyone running a Bitcoin node to easily verify and access the complete state of Citrea. Citrea utilizes $BTC as its native token ($cBTC within Citrea) and aims to provide broader transaction capabilities for OG cryptocurrencies.

Kasar Labs

Kasar Labs is a Starknet engineering and research team dedicated to integrating Starknet’s zk-rollup capabilities with Bitcoin. Recently, they collaborated with Taproot Wizards to launch a data availability adapter, allowing developers to anchor Rollups to Bitcoin.

Kasar’s work also inevitably includes Barknet, a new Bitcoin Rollup that leverages Starknet’s Madara sorter and Cairo VM to harness the power of Starknet’s advanced cryptographic proofs.

Merlin Chain

Merlin Chain is another EVM-compatible zk-rollup game built by the Bitmap Tech team as an L2 solution, scalable across a variety of different Bitcoin-native protocols including Atomicals, Bitmaps, BRC-20s, and Stamps. Merlin Chain recently launched its mainnet and initiated a staking event aimed at fairly distributing the upcoming $MERL governance token. As a result, Merlin Chain has added $2 billion in TVL since February 9th.

Ark

Ark is a novel L2 designed to enhance Bitcoin’s transaction scalability. Unlike traditional approaches relying on state channels or Rollups, Ark introduces a unique method and its virtual transaction outputs (VTXOs), enabling anonymous, off-chain payments. These VTXOs must be used or “refreshed” within four weeks to prevent expiration.

At the core of Ark is the facilitation of transactions through Ark Service Provider (ASP), which are untrusted intermediaries providing liquidity with servers always online, similar to Lightning Network service providers but without requiring users to manage liquidity themselves. This setup allows users to send and receive payments anonymously, protecting their privacy without the complexity of setup procedures like obtaining inbound liquidity.

Key to Ark’s operation is a process called “boosting,” where users can convert on-chain UTXOs to off-chain VTXOs in a trustless manner. Additionally, Ark’s design allows transactions to occur without a direct link between sender and receiver, significantly reducing the on-chain footprint compared to traditional methods like Lightning Network.

The Great Vision

Today, with Bitcoin’s market capitalization surpassing $1.3 trillion, much of the capital on the network remains idle due to limitations in programmability and scalability.

An evolving Bitcoin L2 ecosystem is emerging as a strategic solution to these constraints, experiencing a revival fueled by the rise of Ordinals and the increasingly layered architecture of Ethereum.

This evolution of L2, coupled with growing institutional interest spurred by the launch of the first spot Bitcoin ETF in the United States, lays the foundation for Bitcoin’s adoption resurgence. As these developments unfold, Bitcoin is poised to transition from being primarily a passive store of value to an active, programmable cryptocurrency. This shift has the potential to redefine its role in the broader crypto economy and pave the way for innovation and growth!

Disclaimer：

1. This article is reprinted from [marsbit]. *Forward the Original Title‘Bankless：你应该关注的8个比特币L2’. All copyrights belong to the original author [William M. Peaster]. If there are objections to this reprint, please contact the Gate Learn team, and they will handle it promptly.
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