A look at Bitcoin’s timelocks

Quick Take

  • Bitcoin’s timelock feature enables users to create transactions that can only be spent after a certain time has passed
  • There are four variants of timelocks: nLockTime, nSequence, CheckLockTimeVerify, CheckSequenceVerify

One of Bitcoin’s most valuable features is timelocks. The feature, which has existed since the first release of Bitcoin, enables users to create transactions that are invalid (unspendable) until a certain amount of time has passed. In 2015 and 2016, a handful of Bitcoin Core developers introduced more advanced levels of timelocks, enabling users to create timelocks for individual Bitcoin outputs rather than entire transactions.