Opt-in RBF
A Bitcoin policy allowing unconfirmed transactions to be replaced by a higher-fee version from the same inputs.
Opt-in Replace-By-Fee (RBF) is a Bitcoin transaction relay policy that lets a sender replace an unconfirmed transaction with a new one paying a higher fee, provided the original signaled RBF or the network treats it as replaceable.
This improves fee-bumping and stuck tx recovery but reduces the reliability of zero-confirmation acceptance on networks that use it.
RBF is useful for increasing fee rates during congestion. Wallets may expose "bump fee" or "speed up" features that rely on RBF.
Merchants should avoid accepting 0-conf on chains or wallets that use RBF, or use additional risk checks.
Related Terms
Mempool
→A temporary storage space in a node for pending transactions that have not yet been included in a confirmed block.
Fee Rate
→A fee expressed per unit of transaction size (e.g., satoshis per vbyte) used to prioritize inclusion in blocks.
Zero Confirmation
→Transactions that have been broadcast to the network but not yet included in a block.
Double Spend
→A fraudulent technique where the same digital currency is spent more than once, exploiting the digital nature of cryptocurrency transactions.
Bitcoin (BTC)
→Bitcoin (BTC) is the first and most secure peer-to-peer electronic cash system, underpinned by blockchain technology.
All terms and definitions may update as the Cryptionary improves.
