Bitcoin Core Reference Implementation

Bitcoin Core is the free and open-source reference implementation of the Bitcoin protocol, serving as the canonical software for Bitcoin nodes, miners, and wallet users. Originally released in 2009 by the pseudonymous Satoshi Nakamoto as version 0.1.0 (written in C++ for Windows), the codebase has since been maintained by a global community of contributors, with Wladimir J. van der Laan serving as lead maintainer from 2014 to 2021. Key features: full node: Bitcoin Core runs a fully validating node that independently verifies every transaction and block against Bitcoin's consensus rules, without trusting any third party. It downloads and validates the entire blockchain (over 550 GB as of 2024) from the genesis block (January 3, 2009). Consensus rules: implements all Bitcoin consensus rules including proof-of-work (SHA-256 double hashing with difficulty adjustment every 2016 blocks), block size/weight limits (4,000,000 weight units), BIP (Bitcoin Improvement Proposal) implementations (SegWit/BIP141, Taproot/BIP341, CSV/BIP112, RBF/BIP125). Peer-to-peer network: connects to 8 outbound and up to 117 inbound peers via the Bitcoin P2P protocol (TCP port 8333), exchanging blocks, transactions, and address information. Mempool: maintains an in-memory pool of unconfirmed transactions, sorted by fee rate, for inclusion in candidate blocks. Wallet: built-in HD (Hierarchical Deterministic) wallet following BIP32/44/49/84/86, supporting legacy, SegWit, and Taproot addresses. RPC interface: JSON-RPC API (port 8332) for programmatic control over the node and wallet, with over 200 commands. Mining: built-in block template generation for Stratum miners (getblocktemplate). Pruning: optional pruning mode stores only the last 550 MB of blocks, reducing disk usage. C++ codebase. Cross-platform: Linux, macOS, Windows. MIT.