BOLT is a system for conducting privacy-preserving off-chain payments between pairs of individual parties. BOLT is designed to provide a Layer 2 payment protocol for privacy-preserving cryptocurrencies such as Zcash, by allowing individuals to establish and use payment channels for instantaneous payments that do not require an on-chain transaction.
The libbolt library is a proof of concept implementation that relies on experimental libraries and dependencies at the moment. It is not suitable for production software yet.