Blockstream has activated Simplicity, a new scripting language for Bitcoin, on mainnet and is teaming up with Israeli zero-knowledge specialist StarkWare to pair the language with STARK proofs. The partners say the combination will open the door to more complex smart-contract functionality and fresh approaches to scaling the oldest blockchain. In a parallel push to widen Bitcoin’s utility, AlpenLabs has opened a public testnet for what it calls the network’s first rollup. The zero-knowledge rollup allows developers to build trading, lending and stablecoin applications directly on Bitcoin; it also introduces a BTC-backed “Bitcoin Dollar” and offers compatibility with Ethereum’s EVM. Succinct Labs is providing proof infrastructure, and AlpenLabs plans a mainnet launch once testing concludes. The technical upgrades coincide with growing demand for Bitcoin-backed credit. Lending platform Teller says it has originated US$6 million in USDC loans secured by Bitcoin, while Debifi is advertising loans of US$5,000 to US$700,000 at rates starting at 12.6% APR. Arch Lending, Hodl Hodl and other providers are similarly pitching same-day, non-custodial financing that lets borrowers tap liquidity without selling their coins.