Re-enabling OP_CAT to Unlock Bitcoin’s Programmability
Bruce Liu of OP_CAT Labs is leading a campaign to re-enable the long-disabled OP_CAT opcode in Bitcoin’s Script, aiming to transform Bitcoin from static digital gold into programmable money. Speaking at BTC Asia in Hong Kong, Liu argued that OP_CAT—originally coded by Satoshi Nakamoto and merely commented out—would allow data concatenation in scripts. This change could unlock advanced features such as vaults, covenants, decentralized exchanges and zero-knowledge proofs. Despite past security concerns over denial-of-service attacks, Liu and co-founder Mate Tokay have formed the OP_CAT Alliance to coordinate support from developers, institutions and lawmakers. They’ve demonstrated a Bitcoin fork with OP_CAT enabled, complete with SDKs, APIs and developer tools. The group plans to showcase working DeFi apps on Bitcoin at next year’s conference, challenging the view that Bitcoin should remain limited to payments. If adopted, OP_CAT could rival Ethereum and Solana in Layer-1 programmability and spark a new wave of innovation on the Bitcoin network.
Bullish
Re-enabling OP_CAT is likely bullish for the Bitcoin market. Historically, major protocol upgrades—such as SegWit in 2017 and Taproot in 2021—have enhanced network functionality, spurred developer activity and coincided with sustained price gains. Short-term, the proposal may drive positive trader sentiment as developers and institutions engage with new use cases. Over the long run, unlocking Bitcoin programmability could attract DeFi projects, increase on-chain transaction volume and broaden the network’s utility beyond store-of-value. By positioning Bitcoin to rival Layer-1 chains like Ethereum and Solana, OP_CAT may reinforce Bitcoin’s market leadership and support higher valuations as adoption grows.