BitcoinOS and Starknet are on the verge of adding smart contract functionality to Bitcoin — with, or without, the controversial OP_CAT fork. BitcoinOS and Starknet arent waiting around for the controversial OP_CAT hard fork to add new functionality to Bitcoin, with both projects devising innovative ways to scale Bitcoin using zero-knowledge (ZK) proofs right now. The projects have both demonstrated it’s possible to verify ZK-proofs on Bitcoins existing mainnet even if Bitcoins ultra-simple scripting language makes it difficult and expensive. This could create genuine Bitcoin L2s that inherit much of its security, and unlock the intriguing possibility of creating programmable tokens on Bitcoin itself. Best known as an Ethereum L2, Starknet wants to use the tech to scale Bitcoin to thousands of transactions per second, up from just 7 TPS today. “The ecosystem in Starknet is very, very enthusiastic about also expanding to Bitcoin,” co-founder Eli Ben-Sasson tells Magazine. BitcoinOS, meanwhile, claims it will s...