An introduction to Stacks, the Bitcoin Layer 2 for Smart contracts, Apps, DeFi

Chorus One
Chorus One
March 8, 2024
5 min read
March 8, 2024
5 min read

Since its introduction in 2008, the Bitcoin whitepaper has marked the beginning of a transformative journey. Nations have embraced it as official currency, companies have added Bitcoin to their assets, and in 2024, Bitcoin ETFs are actively being traded. Despite these advancements, Bitcoin has struggled to shed the perception of being merely a store of value, akin to digital gold. While it's true that facilitating smart contracts was not Bitcoin's initial aim, the explosive growth of decentralized finance (DeFi) prompts a thought-provoking question: could the functionalities of DeFi be integrated into Bitcoin?

This is where Bitcoin Layer 2 solutions, or L2s, come into play. Below, we'll delve into one of the most thrilling projects in this realm - Stacks.

⚡️Chorus One is proud to join the latest team of signers on Stacks and further enhance the network’s security and decentralization. Learn more here.


It's widely acknowledged that Bitcoin stands as the most decentralized and secure blockchain. However, the high cost of its block space, low TPS, along with the need for additional computing resources among other factors, have made the development of smart contracts on its platform particularly challenging. This situation paved the way for the emergence of networks dedicated to smart contracting, such as Ethereum. Stacks, however, offers a solution to this issue.

Stacks is a novel layer built atop Bitcoin and it extends the utility of the most secure and decentralized blockchain by introducing smart contracts and dApps functionalities without altering Bitcoin's core protocol. This integration is facilitated through the Proof of Transfer (PoX) consensus mechanism, a pioneering approach that reuses Bitcoin’s Proof of Work (PoW) to secure the Stacks network, enabling smart contracts that directly interact with Bitcoin state and transactions.  The goal of the Stacks layer is to grow the Bitcoin economy, by turning BTC into a productive rather than passive asset, and by enabling various decentralized applications. The Stacks layer has its own global ledger and execution environment, to support smart contracts and to not overwhelm the Bitcoin blockchain with additional transactions. It also provides mechanisms for higher performance, such as fast blocks, decentralized peg, and subnets.

The question of the necessity for a Bitcoin Layer 2 revolves around the potential of integrating fully-expressive smart contracts into Bitcoin. Successfully embedding such functionality could revolutionize Bitcoin's application, ushering in new use cases worth hundreds of billions, including stablecoins, NFTs, and Automated Market Makers (AMMs). This evolution would transform Bitcoin from a passive asset into a cornerstone of digital finance, significantly boosting its demand, value, and utility by enabling a wide array of yet-to-be-explored applications.


For blockchains with native smart contract capabilities, essential features include the ability for smart contracts to be fully secured by the network's security mechanisms, such as hash power in Proof of Work (PoW) systems or staked assets in Proof of Stake (PoS) systems. This ensures that smart contracts benefit from the same level of security as the underlying blockchain. The smart contracts not only need to have ‘read’ but also ‘write’ capabilities. As a layer on top of Bitcoin, Stacks plans to bring these features to Bitcoin through the following elements:

STX: STX, the native token of Stacks, plays a pivotal role in the PoX (Proof-of-Transfer) consensus mechanism, serving two main functions: (a) incentivizing miners to secure the Stacks global ledger, which operates independently of Bitcoin's Layer 1, and (b) ensuring the operational continuity of the sBTC peg by providing rewards to threshold signers involved in the peg mechanism. STX was distributed to the public through the first-ever SEC-qualified token offering in US history and currently enjoys a market capitalization of over $4B.

PoX: Proof of Transfer (PoX) is a unique consensus mechanism to the Stacks blockchain that is designed to leverage the security and robustness of Bitcoin, while allowing Stacks to introduce smart contracts and decentralized applications (dApps) on top of Bitcoin. In typical Proof-of-work (PoW) systems, miners must solve complex mathematical problems. In PoX, miners must transfer a base cryptocurrency (in this case Bitcoin) to join the mining process. This Bitcoin is transferred to STX holders that participate in the network by sta(c)king their STX STX tokens, thus securing the network. So in PoX, you’re bidding Bitcoin in the hopes of being selected to add the next block to the chain versus committing computation power in the case of PoW. Like other networks, the miners on Stacks get block rewards but in STX and not BTC. This dual mechanism integrates the economic incentives of both Bitcoin and Stacks.

Stacking: Stacking is not staking, but the fundamental concept is very similar. Staking involves locking up token X and getting rewards with staking yields in the same token X. Eg - Stake SOL and get rewarded in SOL. Stacking mandates depositing STX tokens to get rewarded in a different token (BTC). This synergy between BTC and STX is interesting and actually incentivizes BTC holders to participate in the STX ecosystem. STX holders on the other side are incentivized to stack their tokens to be rewarded in arguably the most decentralized and secure cryptocurrency token BTC.

Signing: Post the Nakamoto release, the role between Miners and Stackers has been segregated. Where previously, miners decided the contents of the block and also decided whether or not to include them in the Stacks chain, now they would only be deciding the contents of the block and the stackers would be taking on the role of deciding whether to include them in the block or not. Stackers validate and sign blocks through a distributed signing protocol, requiring a significant fraction of locked STX to agree on block inclusion, thus preventing forks and enhancing the chain's integrity. Chorus One is proud to join the team of signers on Stacks along with other industry leaders likeBlockdaemon, NEAR Foundation, DeSpread, Alum Labs, Kiln, Luganodes, Copper, and Figment.

sBTC: sBTC is a fungible token that is pegged 1:1 with Bitcoin to enable Bitcoin holders to participate in the Stacks ecosystem. Users who want to interact with BTC and developers who want to create apps with BTC programmability can both use sBTC, thereby extending BTC’s utility beyond Bitcoin. To deposit BTC into sBTC, a Bitcoin holder would create a deposit transaction on the Bitcoin chain. This deposit transaction informs the protocol of how much BTC the holder has deposited, and to which Stacks address the holder wishes to receive the sBTC. The sBTC system responds to the deposit transaction by minting sBTC to the given Stacks address. To withdraw BTC, a Bitcoin holder creates a withdrawal transaction on the Bitcoin chain. This withdrawal transaction informs the protocol of how much sBTC the holder wishes to withdraw, from which Stacks address the sBTC should be withdrawn, and which Bitcoin address should receive the withdrawn BTC. In response to this transaction, the sBTC system burns the requested amount of sBTC from the given Stacks address and fulfills the withdrawal by issuing a BTC payment to the given BTC address with the same amount.

Clarity: Stacks also has its native programming language called Clarity, crafted with a focus on safety and security. The inspiration for Clarity's development was drawn from analyzing and addressing vulnerabilities commonly found in Solidity. By integrating these lessons, Clarity was meticulously designed to offer a secure coding environment, prioritizing the prevention of exploits right from its core. You can read more about Clarity in the online book - Clarity of Mind.

STX tokenomics

Total supply: ~1.82B

APY: 6% (BTC)

Chorus One and Stacks

We currently support infrastructure for over 50 networks, and we're thrilled to announce that Stacks will mark our inaugural support for a Bitcoin Layer 2 solution. This is a significant milestone for Chorus One, largely due to the exceptional team behind Stacks, whose expertise and dedication have been evident over many years of development.

If you have STX tokens and would like to stack them, feel free to reach out to one of our experts at

To read more about Stacks, we recommend the official documentation available in

About Chorus One

Chorus One is one of the biggest institutional staking providers globally operating infrastructure for 50+ Proof-of-Stake networks, including Ethereum, Cosmos, Solana, Avalanche, and Near, amongst others. Since 2018, we have been at the forefront of the PoS industry and now offer easy enterprise-grade staking solutions, industry-leading research, and also invest in some of the most cutting-edge protocols through Chorus Ventures.

 Join our mailing list to receive our latest updates, research reports, and industry news.
Thanks for subscribing. Watch out for us in your inbox.
Oops! Something went wrong while submitting the form.