Weaving Bitcoin trust into Starknet speed.

A zero-knowledge liquidity layer that enables instant, trustless Bitcoin ↔ Starknet swaps and sub-cent fees/no bridges, no custodians, only proofs.

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Inspiration

The crypto world has long dreamed of a truly trustless Bitcoin–Ethereum connection — but most bridges rely on centralized custodians or oracles that break the core values of decentralization.

We wanted to connect Bitcoin’s unmatched security with Starknet’s scalability and low fees, building a bridge made not of intermediaries, but of math and zero-knowledge proofs. That’s how BitWeave was born — a liquidity layer that lets Bitcoin and Starknet interact natively, instantly, and verifiably.

BitWeave enables users to swap Bitcoin and Starknet assets in seconds, without trusting a bridge or centralized exchange.

Swap BTC ↔ STRK ↔ ETH ↔ WBTC directly using atomic ZK swaps Pay sub-cent fees with Starknet’s rollup efficiency Achieve Ethereum-level security and Bitcoin-level finality Verify all transactions with zero-knowledge proofs, ensuring full transparency and no custody risk Essentially, BitWeave “weaves” liquidity between two worlds — the proof-of-work trust of Bitcoin and the zero-knowledge power of Starknet. What it does

How we built it

We built BitWeave on top of Starknet Cairo v2 smart contracts and integrated Atomiq’s cross-chain swap APIs to handle the Bitcoin side of the transaction.

Core components:

🧩 Cairo Smart Contracts: handle swaps and ZK proof verification 🔒 BTC Relay Contract: verifies Bitcoin block headers and Merkle proofs 🧮 ZK Verifier: checks atomic swap proofs before settlement 🌐 Frontend (Next.js + Starknet.js): wallet connections (Xverse & ArgentX) and real-time swap UI ⚡ Atomic Swap Layer: built with hashed timelock contracts (HTLCs) to guarantee fairness 🔁 Testnet Integration: BTC testnet + Starknet testnet for cross-chain testing

Each swap transaction produces a ZK proof commitment, verified on Starknet before the final exchange.

Challenges we ran into

Designing a ZK-proof flow that’s light enough to verify Bitcoin transactions on Starknet Managing cross-chain timing between Bitcoin’s 10-minute blocks and Starknet’s fast rollups Building a BTC header relay without introducing trust assumptions Testing across two separate wallet ecosystems (Xverse & ArgentX) Keeping gas costs minimal while ensuring security and proof validity Despite these hurdles, the end result is a fully working proof-of-concept that demonstrates instant, non-custodial Bitcoin–Starknet swaps.

Accomplishments that we're proud of

Built one of the first working cross-chain ZK liquidity layers connecting Bitcoin and Starknet Deployed and tested atomic swaps on two independent testnets Proved that Bitcoin’s trust and Starknet’s speed can coexist Designed a future-ready DeFi foundation for multi-chain ecosystems Integrated multiple sponsor technologies (Atomiq, Starkware, OpenZeppelin) into a cohesive architecture

What we learned

How to build verifiable cross-chain protocols using ZK proofs instead of bridges Deep understanding of Starknet’s Cairo ecosystem and its proof system How to integrate Bitcoin primitives (UTXOs, Merkle proofs, HTLC) into L2 logic That user experience is just as important as cryptographic elegance — people need to see trustless swaps happen instantly.

What's next for Weaving Bitcoin trust into Starknet speed.

Mainnet launch with liquidity mining and DAO governance (BitWeave DAO)

Add support for stablecoin pairs (USDC, DAI) and ETH ↔ STRK swaps Integrate with Troves/Endurfi for yield aggregation and auto-rebalancing Publish our ZK-BTC relay paper as open-source infrastructure for the Starknet ecosystem apply for Starknet Foundation Seed Grant and Atomiq Ecosystem funding Explore ZK rollup of Lightning transactions for instant Bitcoin micro-payments on Starknet

Built With

  • argentx
  • atomixap
  • cairov2
  • nextjs
  • open?zeppelin
  • starknetjs
  • xverse
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