Fresh off our recent side event at Bitcoin Vegas 2025 — where together with Sergio Lerner we walked a group of developers and researchers through the inner workings of our latest work — we’re excited to share what’s coming next.

At Fairgate, we’ve been building something new: the Transfer of Ownership Protocol (TOOP) — a BitVMX-based system that enables secure, decentralized transfers of Bitcoin-native assets to and from other blockchains. This extension not only drastically improves the operational costs of cross-chain bridges, but also opens the door to non-fungible asset movement, with no need for predefined recipient addresses or centralized custody.

Now, with the groundwork laid, the Transfer of Ownership paper is live.

Why TOOP Matters

TOOP is a key step in bringing true ownership to cross-chain transfers. Most Bitcoin bridges today rely on semi-custodial models, fronting mechanisms, or predefined parameters that reduce flexibility and trustlessness. TOOP flips that model. Here's what makes it unique:

• Trust-minimized by design: Inherited from BitVMX, the protocol ensures that just one honest operator out of many is sufficient to guarantee the system’s integrity — even in the presence of adversarial participants.
• Powered by BitVMX: TOOP relies on optimistic execution and fraud-proof resolution, using challenge-response interactions to validate off-chain events and computations directly on Bitcoin. This allows bridges to enforce arbitrary logic without protocol changes to Bitcoin.
• No more pre-registered recipients: Unlike previous BitVM-style designs, TOOP allows assets to be unlocked to any address, removing the need for costly pre-registration and enabling flexible asset management across chains.
• No fund fronting required: TOOP eliminates the need for bridge operators to temporarily front funds for user withdrawals. This drastically reduces the cost of operating the bridge and improves user experience by cutting fees.
• Supports non-fungible assets: Whether you're transferring UTXOs, Ordinals, or other unique assets, TOOP is compatible with NFTs — without compromising the security model or requiring special treatment.

From Research to Reality

TOOP isn’t just a theoretical design — It has already been implemented in Cardinal, a system developed by Fairgate and Input Output that wraps Bitcoin UTXOs into Cardano-native NFTs, enabling trust-minimized Ordinal bridging between Bitcoin and Cardano. Through this implementation, TOOP proves its ability to handle both fungible and non-fungible transfers while maintaining high levels of decentralization and composability.

By removing the need for liquidity fronting, TOOP enables a new class of modular, trustless, and cost-effective bridges that can scale with user demand.

This preview is just the beginning—stay tuned for deeper dives into the future of cross-chain ownership.