Callan, also known as “Sap” is the Co-Founder of Threshold Labs, the managing team behind Threshold Network’s tBTC—a trust-minimised bridge enabling native Bitcoin in DeFi. He has been active in crypto full-time since 2017, starting with a data analytics consultancy focused on DeFi. At Threshold DAO, he led key initiatives to bootstrap tBTC liquidity and expand its onchain presence. In 2024, he co-founded Acre Protocol, contributing to token design and liquidity strategy. With a background in finance, computer science, and entrepreneurship, Sap is driven by the belief that Bitcoin will anchor the future of onchain finance.
Wrapped Bitcoin assets are a key gateway into decentralised finance, but not all are built the same.
While most rely on centralised custodians to hold user funds, others are opting to use cryptography and DeFi infrastructure to bring Bitcoin onchain.
One of these alternatives is tBTC, a trust-minimised bridge developed by Threshold Labs.
Instead of handing Bitcoin over to a single institution, users interact with a network of randomly selected nodes operating a Bitcoin multisig — a model designed to minimise custodial risk while maintaining permissionless access.
“We assume 51% of the network is honest, rather than relying on operational guarantees from a centralised custodian,” said Callan “Sap” Sarre, co-founder of Threshold Labs. “That changes the risk model entirely. It’s more about cryptographic trust than institutional trust.”
This architecture sets tBTC apart from options like WBTC or cbBTC, which wrap Bitcoin via regulated entities or exchanges. While these models are more palatable to institutions, Sarre said tBTC appeals to a different crowd — those seeking decentralised rails and broader accessibility without KYC or permissioned entry points.
“We’re not built for institutions just yet. We’re focused on the crypto-native crowd,” he said. “It’s about creating more open access to DeFi using Bitcoin.”
From yield farming to real-world finance
For now, the bulk of tBTC adoption is still among DeFi-native users, with borrowing, lending, and leverage being some of the top use cases.
Threshold’s Bitcoin-backed asset is live on protocols like Aave, Compound, MakerDAO, Gearbox, and GMX.
“It’s boring, but the borrowing use case is actually kind of the most interesting and exciting to me,” Sarre said. “It interfaces with people’s day-to-day lives. They can access liquidity on their Bitcoin and use it to buy a house or a car without needing to sell their coins.”
Still, he believes the current incentive models in DeFi are unsustainable.
“The biggest barrier is yield,” Sarre said. “Anyone can deploy Bitcoin into DeFi now, but the real opportunity lies in how it’s used. I’m interested in building a foundational Bitcoin economy that powers the real world, where people are using Bitcoin not necessarily as a currency, but to finance themselves or earn income.”
Volume over vanity metrics
While many DeFi projects fixate on the total value locked metric as a measure of success, Sarre argues it’s misleading and often rewards short-term incentives over real usage.
“TVL can be inflated by a few large LPs farming protocol points,” he said. “You might have a lot of assets locked, but no actual value being generated or real usage.”
Threshold, by contrast, is seeing substantial Bitcoin throughput despite lower TVL compared to competitors like WBTC. Sarre said tBTC has processed more than 32,000 BTC in volume — a few billion dollars’ worth — with a relatively lean capital base.
“In terms of volume of mints and redemptions, we’re actually surpassing WBTC,” he noted. “We’re positioned less like a static wrapped asset and more like a programmable Bitcoin API.”
Taking Bitcoin multichain
While tBTC currently mints natively only on Ethereum, Threshold is now exploring expansion via what Sarre describes as an ‘application-specific blockchain’ strategy.
The aim is to give developers on various chains native access to Bitcoin liquidity without compromising on decentralisation.
Recent launches on Starknet, Base, and Bitcoin-focused layer 1 Mezo are part of this push, and more are coming.
Sarre said the team is also exploring an appchain focused entirely on tBTC minting and redemption to support lower fees and better native integrations across ecosystems.
Ultimately, Sarre said the vision is less about short-term incentives and more about building the core infrastructure for a usable Bitcoin economy.
“Let’s think about how we can reach the next 100 million people using Bitcoin — or the first billion,” he said.