The ZK rollup debate: Why Bitcoin isn’t there yet

As projects like BitVM innovate, Bitcoin builders call for transparency over misleading buzzwords

article-image

Traxer/Unsplash and Adobe modified by Blockworks

share


This is a segment from the 0xResearch newsletter. To read full editions, subscribe.


Bitcoin enthusiasts often hear terms like “zk rollups” thrown around, but the reality is more nuanced. While Ethereum’s zk rollups rely on zero-knowledge proofs for trustless verification, Bitcoin’s architectural constraints make implementing true zk rollups a distant goal.

Misleading claims around Bitcoin’s layer-2 capabilities and trust assumptions threaten to confuse users, and the Bitcoin builder community is working to clarify these issues.

Ethereum zk rollups leverage the Ethereum mainnet (layer-1) to verify cryptographic proofs directly onchain. Bitcoin, with its 4MB block size and limited scripting capabilities, can’t accommodate these computationally intensive verifiers. As Alexei Zamyatin, a core contributor to BitVM, explains, a zk rollup verifier “simply won’t fit into a block.”

Projects like BitVM take a different approach, combining SNARK-based compression with optimistic verification. Rather than verifying proofs onchain, BitVM splits a program into smaller chunks, each verifiable sequentially. This method mirrors optimistic rollups like Arbitrum rather than Ethereum’s zk rollups.

Screenshot

“The zk part stops at the compression stage,” Alexei notes. “Everything else is an optimistic fraud-proof system.”

The broader discussion about Bitcoin L2s goes beyond just rollups. In a recent thread, Janusz Grzegorz, founder of Bitcoin Layers, reflected on the evolving definition of Bitcoin L2s. Initially, Bitcoin layers evaluated projects based on their claim of being a “Bitcoin L2,” but this approach excluded meaningful activity like BTC-backed tokens on Ethereum L2s.

Janusz advocates for a shift in focus to trust assumptions instead of semantics. He proposes evaluating the bridges that underpin these systems regardless of whether they market themselves as an L2. These include protocols like Rootstock, tBTC on Arbitrum and others.

Grzegorz, known online simply as “Janusz,” also has flagged projects like Merlin and BitcoinOS as having contributed to the confusion. Such projects often market themselves as zk rollups on Bitcoin, despite lacking the infrastructure to deliver security guarantees on par with how the term “rollups” is typically used. He cautions users to scrutinize projects for real progress, such as distributed or optimistic bridges, rather than relying on buzzwords.

For Zamyatin, education and transparency are key. By focusing on trust assumptions, clear definitions and robust analyses, the Bitcoin community can better understand what’s feasible — and what’s not. For now, zk rollups on Bitcoin remain a misnomer, but innovations like BitVM demonstrate how Bitcoin can scale within its unique constraints.

To achieve true zk rollups, Bitcoin will require a soft fork to enable building a native zk verifier. Several new opcodes are currently under consideration amid a recent push to clarify Bitcoin’s future roadmap.

An open Wiki-style forum lets interested stakeholders express their preferences and justify their views. Zamyatin’s team at Build on Bitcoin (BOB) has yet to weigh in, but expects to soon.

“What’s great about this effort is that it collects rationales in one place — instead of fighting on Twitter or scattered threads, you can see the reasoning for each individual’s stance,” Zamyatin said. “It makes it easier to evaluate proposals, summarize pros and cons, and have meaningful discussions.”


Get the news in your inbox. Explore Blockworks newsletters:

Tags

Decoding crypto and the markets. Daily, with Byron Gilliam.

Upcoming Events

Javits Center North | 445 11th Ave

Tues - Thurs, March 24 - 26, 2026

Blockworks’ Digital Asset Summit (DAS) will feature conversations between the builders, allocators, and legislators who will shape the trajectory of the digital asset ecosystem in the US and abroad.

Old Billingsgate

Mon - Wed, October 13 - 15, 2025

Blockworks’ Digital Asset Summit (DAS) will feature conversations between the builders, allocators, and legislators who will shape the trajectory of the digital asset ecosystem in the US and abroad.

recent research

Unlocked by Template (1).jpg

Research

As AI supercharges surveillance, privacy becomes a prerequisite and the winning stack will combine confidentiality with selective disclosure. Zcash’s Tachyon, composable standards on Ethereum/Solana, and compliance-aware pools aim to make private rails the new norm.

article-image

The derivatives giant will extend futures and options access to round-the-clock trading in early 2026

by Blockworks /
article-image

Global fiber network goes live as SEC clears 2Z token for utility use

by Blockworks /
article-image

The SPAC transaction positions Avalanche Treasury Co. as a Nasdaq-listed vehicle for institutional AVAX exposure by 2026

by Blockworks /
article-image

The collaboration brings regulated money market fund exposure to Polygon, with custody provided by Standard Chartered

by Blockworks /
article-image

FG Nexus teams with Securitize to bring its Nasdaq-listed equity onchain, offering tokenized stock trading through Ethereum

by Blockworks /
article-image

Sponsored

Taiko launches binding onchain governance and appoints three directors with expertise in global regulation, business strategy and blockchain tech

by Sponsored /