Boltz

Boltz is a long-established, open-source Bitcoin infrastructure project for atomic swaps between different layers of the Bitcoin ecosystem: the Bitcoin mainchain, the Lightning Network, and the Liquid sidechain. Users swap directly between these networks without ever giving up control of their own keys (hashed-timelock contracts instead of central custody), and entirely without an account, email address, or identity verification - Boltz explicitly states it will never request KYC verification from users. In March 2026, Boltz announced "Boltz USDT Swaps," an expansion enabling instant conversions between Lightning bitcoin and the USDT stablecoin across multiple blockchains (including Ethereum, Arbitrum, Optimism, Polygon), technically using a "routed" swap architecture with tBTC as an intermediate asset. The service is considered trusted infrastructure within the Bitcoin/Lightning community and is integrated in the background by several well-known Lightning wallets. Important note: Boltz suspended its Bitcoin swap service indefinitely on 2026-08-04 after a wave of AI-assisted automated attack attempts against its infrastructure sharply increased - according to the operator, attackers now iterate faster than a team of this size can find and patch vulnerabilities. User funds were never at risk at any point, since Boltz operates non-custodially throughout; unilateral refunds reportedly work independently of the operator's own infrastructure. No resumption date has been given ("do not expect swap services to resume shortly," per the operator).