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Stacks

Status
Mainnet
Type
Sidechain
Fee Token
STX
TVL
₿ 348
Stacks is a sidechain that aims to be programmability layer for Bitcoin. It uses a novel execution environment, Clarity. Stacks uses a hybrid PoS mechanism (PoX) and derives economic security from its native token (STX).
Data Availability
Settlement Assurance
Bridge
Network Operator
Risk Analysis
Bridge Custody
High risk
Users trust centralized companies with custody of BTC
Stacks has no consensus-enshrined BTC bridge. It does have two third-party bridges, which are both custodial multisigs. Users must trust the operators of these bridges to not steal their BTC, as they do not support unilateral exits.
Data Availability
Medium risk
Only Stacks' state roots posted to Bitcoin
Stacks posts state roots to Bitcoin, but not full transaction calldata. Because of this, Stacks' state cannot be reconstructed using only data from Bitcoin. Stacks has a permissionless validator and node operator set which participate in making data availability readily available.
Block Production
High risk
Permissionless Block Production
Stacks has a permissionless block production mechanism, but it does not support exits that circumvent its miner/validator set. This means that users must trust Stacks validators to include their transactions in blocks. Anyone with sufficient capital and resources can participate as a Stacks miner. Only 11 miners are participating in Stacks consensus.
Settlement Assurance
Medium risk
Self-Enforcement of State Validation
Settlement is done offchain, on Stacks, rather than onchain, on Bitcoin. The validity of Stacks state transitions are not enforced by Bitcoin.
Bitcoin Security
Stacks nodes are required for data availability
Stacks posts state roots to Bitcoin, but not full transaction calldata. Because of this, Stacks' state cannot be reconstructed using only data from Bitcoin. Stacks nodes are the sole providers of data availability. Anyone can run a Stacks node and participate in Proof-of-Transfer consensus.
Stacks requires another token to function
The STX token is required to pay for transaction fees and smart contract execution on the Stacks network. It is also used as a reward for miners who participate in the PoX consensus mechanism. The token is indirectly required for the security of the network, as block production by miners is incentivized by STX.
Technology
Clarity
Stacks uses the novel execution environment Clarity. The Clarity language is a subset of Lisp, and is not Turing-complete as a design choice. However, it is still expressive enough to build complex smart contracts and replicate much of the functionalities from Turing-complete environments like the EVM (i.e., DeFi, NFTs, etc.). Stacks is able to read Bitcoin state, due to both Clarity and its integrated PoX consensus mechanism. This allows for events on Stacks to be triggered by Bitcoin activity, or for smart contracts to read Bitcoin state during their execution.
Proof-of-Transfer
Proof-of-Transfer (PoX) is Stacks' novel consensus mechanism, based on Proof-of-Burn. PoX involves Bitcoin miners bidding BTC for the right to mint a Stacks block. The winning miner creates the block, and is rewarded with the STX block reward and STX transaction fees from the block. The miner's bid is paid to STX stackers (stakers). This system allows for STX stackers to earn native BTC yield, and creates an additional revenue stream for miners, similar to merge-mining.
sBTC
sBTC is still in development as of March 2024. It is a bridged version of BTC on Stacks. sBTC is minted by locking up BTC on Bitcoin, and is redeemable for BTC at a 1:1 ratio. sBTC is not yet permissionless, as withdrawals are permissioned by the validator set.
Faster block times
Stacks operates at the same block times as Bitcoin as of March 2024, roughly 10 minutes per block. However, the upcoming Nakamoto Upgrade in April 2024 will reduce block times to an order of seconds.
Lower fees
Stacks fees average in the order of tens of cents as of March 2024.
Use Cases
DeFi
The most popular use case for Stacks is DeFi. Stacks has a number of DeFi applications, including lending, borrowing, and decentralized exchanges.
NFTs
Stacks is home to a number of NFT projects, including digital art, collectibles, and indentity.
Operator
Stacks is operated by miners and validators
Block production is managed by Stacks miners (which are typically also Bitcoin miners, similar to the node overlap with classic merge-mining), by combining microblocks created by Stacks validators. Users trust the majority of validators and miners to not collude or censor.
Withdrawals
Users trust centralized operators to process their withdrawals
Stacks users deposit BTC into Stacks through custodial bridge mechanisms. They trust that the operators of these bridges (e.g. aBTC and xBTC) will not steal their Bitcoin assets, or censor their withdrawals.
Source Code
Code is open-source
All code related to the Stacks project is free and open source.