Bitcoin Unlimited

Bitcoin Unlimited (BU) is a full node implementation for Bitcoin Cash networks. The Bitcoin Core client, from which Bitcoin Unlimited is forked, has a hard coded one megabyte block limit; Bitcoin Unlimited differs by allowing users to signal which block size limit they prefer, find the limit having a majority consensus and automatically track the largest proof-of-work, regardless of block size. However, if a block greater than one megabyte in size is accepted by Bitcoin Unlimited and rejected by nodes with a block size limit, a fork of the network will occur, resulting in two separate blockchains with Bitcoin Unlimited nodes following the chain with the largest proof-of-work.

The release of Bitcoin Unlimited follows the release of Bitcoin XT and Bitcoin Classic, alternative proposals which aimed to increase bitcoin's transaction capacity of around 2.5-3 transactions per second by increasing the hard-coded block size limit.

As of version 1.1.0.0, Bitcoin Unlimited releases are compatible with Bitcoin Cash, a cryptocurrency that split from bitcoin and allows larger blocks.