Alpen: smart contracts, proven on Bitcoin

Many Bitcoin Layer 2 solutions rely on trade-offs. Alpen is trying something different — a full zk-rollup with EVM compatibility, where every state update is cryptographically proven and written directly to Bitcoin. This isn’t a wrapped BTC token or a federated bridge. It’s an attempt to bring real programmability to Bitcoin without giving up security or decentralization.

What is Alpen?

Alpen is a validity rollup that doesn’t rely on external consensus systems or separate data layers. It uses Bitcoin itself for both settlement and data availability, making it the anchor of truth for every transaction.

Each state transition is proven using zero-knowledge proofs and posted to Bitcoin. Once recorded in a Bitcoin block, the transaction is considered final — not because of a signature or majority vote, but because it’s been verified cryptographically and embedded into the most secure chain in existence.

This model brings smart contracts and programmable applications directly onto Bitcoin’s foundation — without changing how Bitcoin works.

Investments

In early 2025, Alpen Labs raised $8.5 million in a strategic round led by Castle Island Ventures, with participation from Coinbase Ventures, OKX Ventures, and many others. The funding supports further development of the rollup, its bridge, and the tooling stack surrounding zk proofs on Bitcoin.

Why that matters

If you’ve ever tried to build something on Bitcoin, you’ve probably run into the limits. The scripting language is intentionally restrictive, and workarounds often involve trusting custodians, relying on centralized bridges, or settling activity outside of Bitcoin entirely.

Alpen offers an alternative. Its architecture enables developers to create things like recurring payments, programmable vaults, or stablecoins backed by actual BTC. It also allows for account-level logic, such as spending limits or time delays, and even privacy-enhanced transactions.

One of the more recent applications is BTD, a Bitcoin-backed stablecoin Alpen is building using Liquity V2. It’s designed to be censorship-resistant and fully native to Bitcoin, without relying on wrapped tokens or federated custody. It also keeps settlement on Bitcoin.

Instead of bending Bitcoin’s rules, Alpen extends its functionality through proofs and commitments, in a way that respects the chain’s design while making it more expressive.

How it works

Alpen recently shared a visual breakdown of their testnet architecture on Signet, giving a detailed view of how execution and orchestration layers interact.

Execution layer: Alpen runs on Reth, an Ethereum client that supports Solidity smart contracts and Ethereum tooling. Developers can reuse code and infrastructure from the EVM ecosystem.

**Bridge layer:** The Strata bridge connects Alpen to Bitcoin using a 1-of-N challenge model. Any participant can submit or contest a claim, ensuring trustless interaction.

**Rollup mechanism:** State transitions are posted as commitments to Bitcoin. Blocks are produced every 5 seconds with a gas limit around 30 million.

Account abstraction: Alpen includes support for ERC-4337-style account abstraction, enabling custom wallet logic and sponsored gas.

This setup enables open participation and Bitcoin-level finality for apps built with Ethereum’s flexibility.

What they’ve built so far

One major milestone is the core logic for the Strata bridge, built on BitVM2 designs and using a purpose-built 1-of-N challenge structure for BTC — Alpen transfers.

The team is also integrating BitVM2 ideas into their architecture. Public documentation shows how proof validation and challenge-response schemes are already being used, with some parts running off-chain to improve speed and reduce costs.

What’s next

The team says the testnet is coming soon, and it will launch on Bitcoin Signet. In this initial phase, state commitments are written to Signet blocks, which means the system behaves more like a commit chain than a full rollup. However, the plan is to move to full mainnet support and on-chain data availability in future releases.

From what’s been shared publicly, most of the critical infrastructure is already functional.

Hiring

In June 2025, Alpen shared an open role for a Partner Operations Manager — someone who would support and coordinate onboarding for ecosystem partners. The listing highlights Alpen’s growing momentum and commitment to ecosystem support.

“The most important thing that’s ever happened in blockchains is uniting Bitcoin’s collateral base with rollup assurances and programmability. It will throw the rest of the ecosystem into absolute chaos as Bitcoin reaches its destiny.” — Nic Carter

Alpen isn’t trying to make Bitcoin into Ethereum. Instead, it’s trying to answer a harder question: what if Bitcoin could host real applications — with privacy, logic, and expressiveness — while still doing what it does best?

It’s still early, but if the vision holds, Alpen could be one of the most meaningful steps toward making Bitcoin programmable in a way that respects its roots.

To explore the project in more detail, visit: https://alpenlabs.io

You can also read the full technical documentation here — it was recently updated with new details on Strata, bundling, and system architecture: https://docs.alpenlabs.io

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