What it does
Boltz connects Bitcoin networks through swaps whose states cover payment, confirmation, claiming and refunds. Its developer clients handle the cryptography and recovery work behind those transfers.
Boltz distinguishes three directions: on-chain Bitcoin to Lightning, Lightning to an on-chain address, and transfers between supported chains. A swap locks funds under conditions that allow the intended exchange or a later recovery path. Understanding which side must claim or refund the funds matters when a transfer stops partway through.
For an on-chain-to-Lightning swap, the receiving wallet provides a Lightning invoice and Bitcoin is sent to the swap's lockup address. If paying that invoice fails, returning the locked Bitcoin requires a refund transaction. An expired swap should not receive a new deposit. An expiry label also does not prove that previously deposited funds have already returned.
The reverse direction works differently. The Lightning payment is held while the on-chain payment is prepared, and the client must claim the on-chain funds. If a failed reverse swap expires, the Lightning funds return automatically. Failed on-chain-to-Lightning and chain-to-chain swaps instead need refund or rescue information and an actively broadcast refund transaction. Preserve that information until the operation is finished.
Developers should start with an official client or software toolkit. Boltz recommends Boltz Client for many server integrations and Breez SDK Nodeless for mobile or browser integrations. The libraries handle cryptographic signing, status changes and recovery cases; Boltz warns that errors in a custom direct integration can lose funds. An application still needs to show whether funds are awaiting confirmation, claimed or being recovered.
Liquid routes have an additional network consideration. The Liquid Federation's October 20, 2026 notice describes provider-mediated BTC/LBTC swaps resuming while direct Federation withdrawals from Liquid remain restricted. It treats restoration of full one-to-one Bitcoin backing and direct withdrawals as a later phase. That notice does not establish the availability of a particular Boltz route, so check the route and receiving network before sending funds.
Strengths
- Separates swap progress from the claim or refund needed to finish it
- Official client libraries cover recovery cases as well as creating swaps
Watch out for
- Some failed swaps require keys or rescue information and a refund transaction
- Liquid routes are affected by the network's staged restoration
Best for
- Developers integrating Bitcoin and Lightning swaps
- Users checking what a pending or failed Bitcoin swap means
Sources
- Boltz Backend overview and integration guidance (Oct 27, 2026)
- Boltz swap types and lifecycle states (Oct 27, 2026)
- Boltz claims and refunds (Oct 27, 2026)
- Boltz clients, software toolkits and libraries (Oct 27, 2026)
- Liquid Network Staged Recovery Update, October 20, 2026 (Oct 27, 2026)