Bitcoin is no longer the old Bitcoin! For years it just functioned like a digital safe – it kept your money safe but couldn’t do much else. Now, however, a real revolution is underway. Bitcoin second layer projects came and changed everything. These new technologies are like bridges that bring speed, low fees and smart applications to the Bitcoin world.
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When Bitcoin NFTs hit the headlines, Bitcoin network fees skyrocketed. At that mome, everyone understood that a solution was needed. This article is the story of this evolution – how the best Bitcoin second layer projects can transform it from a simple store of value to a full financial ecosystem. Not in technical and complicated language, but in a way that you can make smart decisions in this exciting space.
Why does Bitcoin need a second layer?
To understand the importance of second-layer solutions, we must first familiarize ourselves with a key concept in the world of blockchain: “Blockchain Triple”. This concept states that a network cannot be fully secure, deceralized and scalable at the same time. Satoshi Nakamoto, the creator of Bitcoin, consciously prioritized security and deceralization, sacrificing scalability for these two fundameal principles. This smart choice made Bitcoin the most secure network in the world, but it also brought practical challenges.
The main problems of the first layer (Layer 1) of Bitcoin are:
- Low Transaction Speed (TPS): Bitcoin can only process about 7 transactions per second (TPS). This figure is very small compared to traditional payme networks such as Visa, which process thousands of transactions per second, making it difficult to use Bitcoin for everyday paymes.
- High transaction fee: At times when demand for network usage increases (such as during the peak of Ordinals’ popularity), limited block space creates iense competition and skyrocketing fees. This makes small transactions uneconomical.
- Limited programmability: The Bitcoin scripting language (Script) is ieionally designed to be simple and limited. This limitation protects the network from attacks, but preves the implemeation of complex smart coracts and deceralized applications, similar to what we see in Ethereum.
The second layer (L2) solutions, as protocols built on the Bitcoin blockchain, solve these problems. They greatly increase speed and reduce costs by moving the bulk of transaction processing off the main chain, while still relying on the first layer of Bitcoin for security and final settleme. For more information read our article What is the second layer of Bitcoin.
This structure allows them to inherit Bitcoin’s unparalleled security and at the same time add new capabilities like smart coracts to this ecosystem, without the need to change Bitcoin’s conservative core protocol.
Comprehensive review of the best Bitcoin second layer projects
Now that we’ve covered the basics, let’s delve deeper io the most promine second-layer Bitcoin projects. Each of these projects offers a unique approach to expanding Bitcoin’s capabilities. The best Lasse II Bitcoin projects are:
1. Lightning Network
- Iroduction: Lightning is the oldest and most well-known second layer of Bitcoin, designed to solve the problem of micropaymes and everyday transactions with high speed and low cost.
- Technology and how it works: This network works on the basis of “Payme Channels”. By locking some bitcoins in a multi-signature wallet, two users create a channel and can instaly transact endlessly between themselves. Lightning network transactions occur off-chain, and only when the channel is closed is the final settleme recorded on the Bitcoin blockchain.
- Strengths: Incredibly high speed (up to 1 million TPS in theory), almost zero fees for in-channel transactions, and increased privacy because not all transactions are recorded on the main chain.
- Weaknesses and challenges: Complexity in channel liquidity manageme, the need for users to be online (or use watchdog services) to preve fraud, and the risk of liquidity conceration in large nodes that can become ceral hubs.
2. Stacks
- Iroduction: Stacks is a unique second layer that brings the ability to run full smart coracts and build deceralized applications (dApps) directly io the Bitcoin ecosystem.
- Technology and how it works: Stacks uses an innovative consensus mechanism called Proof of Transfer (PoX). In this model, by sending Bitcoin (BTC) to the network, miners earn the right to produce new blocks and receive the native token Stacks (STX). In return, STX holders can “stack” their tokens and receive bitcoins se by miners as rewards. Its programming language, Clarity, is designed with a focus on security and predictability.
- Strengths: Very high security due to the 100% finality of transactions with Bitcoin (Bitcoin Finality), which means that to restore a transaction in Stacks, the Bitcoin blockchain itself must be restored. The economic model of PoX creates an ieresting symbiotic relationship between the two networks. Stacks was also the first project to receive its token sale license from the US Securities and Exchange Commission (SEC).
- Weaknesses and challenges: Transaction speeds were slower than other L2s in early versions (improved by Nakamoto’s update), its ecosystem is still growing, and it faced criticism about ceralization early on.
3. Rootstock (Rootstock – RSK)
- Iroduction: As the oldest Bitcoin smart coract sidechain, RSK is designed to be fully compatible with the Ethereum Virtual Machine (EVM).
- Technology and how it works: The security of the RSK network is provided through Merged Mining. This mechanism allows Bitcoin miners to simultaneously mine and verify RSK blocks without the need for additional computing power. Its native token, RBTC, is pegged to BTC at a 1:1 ratio and transferred via a two-way bridge called Powpeg.
- Strengths: Full compatibility with EVM allows Ethereum developers to easily port their applications to the Bitcoin ecosystem. Its security is very high due to the participation of more than 60% of the hashrate of the Bitcoin network in the combined mining. Also, the fees are much lower than Ethereum.
- Weaknesses and challenges: Despite the high poteial, the volume of total value locked (TVL) and its ecosystem is still smaller than that of major EVM competitors. Dependence on bridges to transfer assets is always a poteial security weakness, and Powpeg’s federated model also faces criticism.
4. Liquid Network
- Iroduction: Developed by Blockstream, Liquid is a sidechain specifically designed to facilitate fast, cheap and confideial transactions between exchanges, financial institutions and professional traders.
- Technology and how it works: The Liquid network operates on a federated model. A group of 15 reputable companies in the crypto field (Functionaries) are responsible for producing blocks and managing network security. Its outstanding feature is Confideial Transactions, which hide the amou and type of assets transferred from public view and provide high privacy.
- Strengths: A fixed block time of 1 minute and transactions finalizing in 2 minutes make it ideal for quick settlemes. High privacy is a big advaage for big traders. This network also supports the issuance of other assets (Issued Assets) such as stablecoins.
- Weaknesses and challenges: Its biggest weakness is the high risk of conceration due to the federal model. This model conflicts with Bitcoin’s philosophy of deceralization, and its adoption outside the circle of exchanges and institutions has been limited.
5. Merlin Chain
- Iroduction: Merlin Chain is one of the most rece and successful second layer projects of Bitcoin, which managed to attract a huge amou of Total Value Locked (TVL) shortly after its launch in 2024.
- Technology and how it works: This project uses advanced ZK-Rollup technology. Transactions are collected and processed in the second layer, and then a hard cryptographic proof of their autheicity is se to the first layer of Bitcoin. This approach inherits Bitcoin’s security while providing high scalability. Merlin also leverages a deceralized oracle network and fraud-proof modules for enhanced security.
- Strengths: Very high scalability and low fees thanks to ZK-Rollups technology. The project is EVM-compatible and has a special focus on supporting native Bitcoin assets such as BRC-20 and Ordinals, making it attractive to existing users of the ecosystem.
- Weaknesses and challenges: As a very new project, it has yet to stand the test of time. As with most rollups, there are risks involved in having a ceralized Sequencer (responsible for sequencing transactions). Criticisms have also been raised regarding the prolonged release time of staked assets in its early campaigns.
6. Nervos Network (CKB)
- Iroduction: Nervos takes a differe approach. The project itself is a proof-of-work (PoW)-based first-layer blockchain that, with its multi-layered and flexible architecture, acts as a secure settleme layer for a variety of second-layer solutions. Its connection with Bitcoin is specifically established through the innovative RGB++ protocol.
- Technology and how it works: Nervos uses the Cell model, which is a generalized version of Bitcoin’s UTXO model. Each cell can store data and state, which provides great flexibility for building dApps. Its virtual machine CKB-VM is based on RISC-V architecture and allows developers to use differe programming languages. The RGB++ protocol connects Bitcoin UTXOs to CKB cells using the “isomorphic connection” technique, bringing smart coract capabilities to Bitcoin without the need for traditional bridges.
- Strengths: Very high flexibility in architecture, strong security based on PoW, and high ieroperability with other blockchains. The RGB++ approach provides a native and secure solution for extending the capabilities of Bitcoin.
- Weaknesses and challenges: The high technical complexity of this project makes it difficult for ordinary users and investors to understand. This project needs better marketing and education to achieve widespread adoption.
7. RGB protocol
- Iroduction: RGB is a smart coract system that works directly on Bitcoin and the Lightning Network, with a primary focus on privacy and scalability.
- Technology and how it works: RGB uses a revolutionary model called Clie-Side Validation. In this model, the smart coract data is maiained and verified by the parties involved in the transaction instead of being stored on the public blockchain. To preve double spending, a concept called Single-Use Seals is used, which are attached to Bitcoin UTXOs.
- Strengths: Unrivaled scalability and privacy, as no sensitive or bulky data is recorded on-chain. The protocol does not require a native token and is fully compatible with the Lightning network, enabling insta and private transactions.
- Weaknesses and challenges: This technology is very new and complex. Its user experience is challenging because users are responsible for maiaining their own data and must be online to ieract. This protocol is still in the early stages of developme and adoption.
Comparison of the best Bitcoin second layer projects
To help better understand the key differences between these projects, the table below provides a quick comparison based on importa criteria.
| Project | The main technology | Security model | speed (TPS) | Finalization of the transaction | Main uses | Conceration risk |
| Lightning | Status channel | Full inheritance from Bitcoin | Very high (up to 1 million theory) | immediate (in-channel) | Small paymes, daily paymes | Medium (risk of liquidity conceration in hubs) |
| Stacks | Sidechain (PoX) | 100% finalization with Bitcoin | ~10-20 (faster after Nakamoto) | ~10-20 minutes (with Bitcoin) | dApps, DeFi, NFT, digital ideity | Bottom (deceralized network of stackers) |
| Rootstock | Sidechain (Merged Mining) | Hybrid Mining (Common Security) | ~20-300 | ~30 seconds | dApps compatible with EVM, DeFi | down (depends on bitcoin miners) |
| liquid | Sidechain (Federal) | Federation of 15 members | ~7-10 | ~2 minutes (2 blocks) | Transactions between exchanges, issuance of assets | Above (corolled by the Federation) |
| Merlin Cheyne | ZK-Rollup | Full inheritance from Bitcoin | ~1000+ (theory) | ~10-60 minutes (with Bitcoin) | DeFi, GameFi, BRC-20 ecosystem | Medium (depends on Sequencer) |
| Nervous (CKB) | PoW L1 + L2 | PoW (Very Secure) | variable (depending on L2) | Fast (in L2), final with CKB | Ieroperability, RGB++, digital assets | down (deceralized PoW network) |
| RGB | Clie-side | Full inheritance from Bitcoin | Very high (limited to P2P network) | immediate (between parties) | Issuance of private assets, confideial NFTs | very low (inherely deceralized) |
The Architecture of Bitcoin’s Second Layers: Iroduction to Key Technologies
Bitcoin second layer projects use differe technical architectures to achieve their goals. Understanding these differences is esseial to evaluate the benefits and risks of each project. These architectures form a spectrum of security models ranging from direct Bitcoin security to trust-based models.
State Channels
These solutions work by creating a private, off-chain channel between two or more parties. Participas can make an unlimited number of transactions instaly and at almost zero cost within this channel. Only transactions related to opening and closing the channel are recorded on the main Bitcoin blockchain and the final balance is settled.
- Basic example: Lightning Network, which is specifically designed for micropaymes.
Sidechains
What are side chains or side chains? There are independe blockchains that are connected to Bitcoin through a two-way peg and allow the transfer of Bitcoin between the two chains. These networks have their own consensus mechanism and security model, which can be differe from Bitcoin.
Their security depends on their own validators or federation members, rather than relying directly on Bitcoin miners, which has led to some debate about whether sidechains are truly a second layer.
- Examples: Rootstock (RSK), Liquid Network and Stacks use this architecture.
Rollups
Rollups are known as one of the most secure scaling solutions. They process hundreds of transactions in the second layer and then compress their data, as a single transaction, io the first layer of Bitcoin. This method ensures that the data necessary to verify transactions is always available and secured by the Bitcoin network, providing much higher security than sidechains.
- Basic example: Merlin Chain which uses ZK-Rollups technology to achieve this goal.
Challenges and future prospects of the second layer ecosystem of Bitcoin
Despite all the exciteme and innovation, Bitcoin’s second-layer ecosystem still faces significa challenges to overcome.
- Common challenges:
- Technical complexity and user experience: Many of these solutions are still complex for the average user and require technical knowledge.
- Liquidity and network effect: The success of networks like Lightning depends on sufficie and widespread liquidity, which takes time to build.
- Conceration risks: As we have seen, some projects make compromises in deceralization to achieve speed and efficiency, which can be a disadvaage.
- Ieroperability: The lack of a single standard between differe second layers can lead to the creation of fragmeed and isolated ecosystems and make it difficult to transfer assets between them.
However, the outlook for the future is very bright. The future of Bitcoin will be a multi-layered future. The first layer will remain the anchor of security and the final settleme layer, while the second and even third layers will host economic activity, innovation and applications. With the adve of newer technologies such as BitVM And as curre projects mature, Bitcoin will transform from a passive asset to a productive asset and the main underpinning of the future deceralized economy.
Frequely asked questions
Security depends on the model of each project. Solutions like rollups and the Lightning network inherit their security directly from the Bitcoin network and are very secure. Sidechains have differe security models (such as hybrid mining or federation) that require differe levels of trust. However, there are always risks associated with smart coract bugs on any platform.
The main purpose of the second layers of Ethereum is to solve the problem of scalability and reduce costs. In corast, the second layers of Bitcoin, in addition to scalability, seek to add completely new capabilities such as complex smart coracts that are not prese in the first layer of Bitcoin.
Poteially yes. As Bitcoin’s utility increases and it becomes a productive asset in DeFi (e.g. as collateral for loans), the demand to hold and use BTC could increase, poteially leading to an increase in its value.
The main risks include technical risks (the presence of bugs in the code), adoption risk (iense competition between projects and insufficie user acquisition), and inhere dependence on the long-term success and stability of the Bitcoin network. Also, many of these projects are new and have yet to stand the test of time.
summary
After this comprehensive review, we return to the main question: which project is the best? The smart answer is that there is no absolute best. The optimal choice depends eirely on your needs and use. Each project excels in a specific area and is designed to solve a specific problem.
- For fast and cheap everyday paymes, the Lightning Network is unbeatable.
- To build fully deceralized dApps with the ultimate security of Bitcoin, Stacks is the best choice.
- For developers looking to access the massive EVM ecosystem, Rootstack Bridge is ideal.
- For institutions and traders who need speed and privacy, Liquid Network is the perfect solution.
- For those who wa to operate on the cutting edge of ZK technology and the BRC-20 ecosystem, Merlin Chain is the most attractive option.
These projects aren’t just technical updates; They are rewriting the Bitcoin narrative. They are transforming Bitcoin from a static digital asset to a global, dynamic and programmable financial platform. This great revolution has just begun and the future of Bitcoin looks brighter than ever thanks to these innovations.
