When we talk about "BTC Layer 2," we're actually referring to a vision: to give Bitcoin greater scalability and programmability without changing its underlying consensus mechanism. There have been many attempts in this direction, such as Stacks, Merlin, and Hemi. However, I've always believed that Stacks and Hemi are truly worthy of comparison: one is an established solution, the other a newcomer, but their technical approaches are drastically different, which makes the comparison more valuable.
Stacks was many people's first encounter with Bitcoin scaling protocols. It built its own chain and introduced the Clarity language to implement smart contracts. It also achieved a degree of security inheritance by writing block state to the BTC main chain through a method called "anchoring to Bitcoin." However, Stacks is essentially more like a "parallel chain" than a "Layer 2." It cannot read or interact with Bitcoin's state in real time; in other words, Bitcoin is static and imperceptible to it. This model is closer to an "independent chain attached to BTC."
Hemi's approach, on the other hand, is very different. Instead of attempting to reinvent a contract language, Hemi is directly compatible with the EVM, meaning developers can directly use Solidity to develop smart contracts. More importantly, Hemi builds two core modules: hVM and hBK. hBK is a toolset that natively accesses the Bitcoin chain state. This allows Hemi smart contracts to detect whether a UTXO has been spent, whether an address has received funds, whether a BTC transaction has been recorded on-chain, and even to act as a condition for triggering certain on-chain behaviors.
You'll find that the biggest difference between Stacks and Hemi isn't performance, but rather the ability to "understand the BTC state." In my opinion, this is the true standard that determines whether something deserves the name BTC L2.
Many say Stacks has a more mature ecosystem and an earlier community, but this is precisely its bottleneck: the ecosystem is accustomed to a development model with almost no interaction with BTC itself. Hemi, from the beginning, wasn't about creating a "chain next to Bitcoin"; it's about making Bitcoin a first-class citizen and integrating it into the world of smart contracts. It's not just about supporting the use of BTC assets; it's about making BTC state an integral part of the contract logic.
From a security model perspective, Stacks relies on an on-chain "anchoring" mechanism, but it lacks true irreversible state verification. Hemi's Proof-of-Proof (PoP) mechanism, on the other hand, directly anchors Hemi's state hash into Bitcoin blocks, making it unchangeable once written. This means that even if Hemi itself rolls back or is attacked, it cannot modify the chain state already recorded by Bitcoin. This ultimate endorsement is the closest I've seen to "BTC ontology trust."
Of course, if you just want to create a DEX or a regular contract application, Stacks is sufficient. But if your ambition is to build a DApp that truly understands BTC and uses BTC behavior as input variables, then Hemi is clearly a more suitable environment.
It's like having a friend who understands you versus someone standing next to you who doesn't understand you—I'd rather choose the former. Hemi understands BTC not through a middle bridge or oracle, but through native reading and logical integration. This respect for and integration at the underlying design level is the right way to approach BTC Level 2 in my mind. @Hemi $HEMI #Hemi
