Boltz Exchange: Building the Rails Between Bitcoin Layers
Lightning.News Editor’s Note
Boltz exemplifies a quiet but critical transformation: Bitcoin moving from ideology to infrastructure. For executives watching the evolution of financial rails, the company’s approach, trustless, compliance-aware, and API-centric, offers a glimpse of how future financial systems will interconnect.
As Bitcoin matures, a new frontier is emerging: the ecosystem of Bitcoin layers. Beyond the mainchain, sidechains like Liquid or Rootstock, Arkade, and the Lightning Network are redefining how digital value moves, faster, cheaper, and increasingly programmable. But these systems don’t exist in isolation; they need bridges that work seamlessly and securely.
Boltz builds those bridges. Co-founded by Kilian Rausch, Boltz has evolved from a technical experiment into a core piece of Bitcoin infrastructure, connecting on-chain Bitcoin, Lightning, Liquid, Rootstock, and Arkade through trustless atomic swaps.
In this conversation, we explore how the project started, why China was the unexpected launchpad, and what Bitcoin finance could look like when banks become protocols rather than custodians.
Interview
Janusz: Kilian, you’ve been around Bitcoin since the early years. How did that happen?
Kilian: By accident. Back in late 2015, I was living in China and working for a German automotive company. I discovered Bitcoin almost randomly and soon joined BTC China, which at the time was one of the world’s largest exchanges and also operated a top-three mining pool. Those were the wild days before the 2017 ban.
Janusz: So you experienced the Chinese crypto scene before it was shut down.
Kilian: Yes. It was the best place to be, open, innovative, and buzzing with energy. When the government banned trading in 2017, I’d already seen how large-scale Bitcoin operations could run. That experience shaped how I think about liquidity and infrastructure today.
From Decentralized Exchange to Bridge Service
Janusz: How did Boltz begin?
Kilian: Originally, Boltz was a helper tool for an ambitious decentralized exchange project built on top of the Lightning Network. That exchange failed, too early for its time, but Boltz survived as a side service managing users’ Lightning channel balances. The “side project” became the company.
Janusz: And you officially launched in 2019?
Kilian: Yes, April 2019. It’s been six years since then, and only now we’re seeing our work truly pay off as Bitcoin’s multi-layer ecosystem takes shape.
Where Lightning Really Stands
Janusz: Let’s talk about Lightning. It’s often either overhyped or underestimated. Where do you see it today?
Kilian: Lightning only began finding real adoption around 2024. The technology was never the problem, the misunderstanding was. It was handed directly to end users, which doesn’t work. Managing channels, liquidity, uptime, it’s all complex.
Janusz: So, how should it work instead?
Kilian: Let applications abstract it away. Keep the user experience simple, use something like a sidechain wallet (for example, on Liquid) for storage, and swap in or out, e.g. via Boltz, when Lightning speed is needed.
Janusz: For readers less technical, explain Liquid in business terms.
Kilian: Liquid is a Bitcoin sidechain: Bitcoin locked on the mainchain is represented as Liquid BTC. It moves faster (1-minute blocks), supports confidential transactions and asset issuance, and is tailored for institutional use. It’s not a “better Bitcoin”, just optimized for different trade-offs: more efficiency and features, less decentralization.
The Big Picture: Connecting Bitcoin’s Layers
Janusz: So we have the Bitcoin mainchain, which works as the core ledger and ultimate source of truth: immutable, secure, but heavy and slow. It’s the foundation where final settlement happens, much like a global clearing house that never lies. What is Liquid?
Kilian: Alongside Bitcoin runs Liquid, a Bitcoin-anchored sidechain designed for faster, more confidential transactions. It runs one-minute blocks, supports private transfers, and enables the issuance of digital assets such as stablecoins or tokenized securities. For institutions, Liquid matters because it combines Bitcoin’s integrity with enterprise-grade performance, ideal for settlement, treasury flows, or asset issuance that requires speed and discretion.
Janusz: And above these layers comes the Lightning Network, a real-time payment layer optimized for instant, near-zero-cost transfers. Instead of waiting for on-chain confirmations, it routes payments through secure peer-to-peer channels. Lightning matters because it enables global instant settlement, from microtransactions to business-to-business transfers, unlocking new use cases in fintech, commerce, and digital infrastructure.
Where does Boltz fit in?
Kilian: We’re the bridge between these layers. Without us, moving Bitcoin between them can take many hours or require technical setup. With Boltz, it’s a one-click swap, instant and trustless. The ease and speed of Boltz swaps even enables new use cases, like an entire new wallet class of swap-based Lightning wallets like Aqua or the Bull Bitcoin Wallet. Regarding Lightning, one could say it sits “in between” the layers; we see it as the connective layer linking them all.
Bitcoin Finance Comes of Age
Janusz: You’ve mentioned “Bitcoin finance.” What do you mean?
Kilian: Until recently, Bitcoin was about holding or spending. Now, new Bitcoin layers enable, for instance, lending and yield, meaning you can use Bitcoin as collateral for loans or earn interest by lending it out.
Janusz: That sounds like DeFi on Ethereum.
Kilian: Exactly, but with Bitcoin as the native asset. We take the proven mechanisms from EVM ecosystems, strip out the tokens, and use Bitcoin instead.
Institutions Are Re-architecting
Janusz: How are banks reacting?
Kilian: We’re already seeing a shift. Sygnum Bank in Lugano is working with Debifi on Bitcoin-collateralized loans using multi-sig custody. That’s a new mindset: banks moving from custody to co-signing.
In five years, I see some banks operating as protocols rather than custodians, earning on lending volume but no longer holding client assets directly.
Janusz: That’s a huge structural change.
Kilian: Yes, and it aligns with how AI transforms commerce, where services become APIs that interact with AI agents. I am convinced, banks will follow that path too.
Personal Motivation and Business Reality
Janusz: What keeps you personally motivated?
Kilian: I’m a user of Boltz myself. We use Boltz internally every day and many features we built for ourselves. Ultimately, we want native Bitcoin finance products that truly work without custodians. And Boltz is a for-profit company, we live from what we build. There’s no VC money, so we focus on sustainable business, not hype.
Janusz: What are the challenges without external funding, which is a bit of an outlier in the ecosystem, and what lessons can other founders draw in the quest for “staying profitable?
Kilian: I am not going to lie, you’ll probably have to go through some hardship, at least in the early phases of bootstrapping. For example, for us, that meant moving off the cloud and hosting Boltz on our self-built servers to save thousands of dollars in cloud costs per month. Also, we practically don’t spend any money on marketing or sponsoring and handle everything ourselves, including customer support. Further, my lesson learned is that hiring conservatively is not only great for finding great people but also incredibly important to keep a decent financial security buffer for potential revenue drops.
For Enterprises: Why Integrate Bitcoin
Janusz: Let’s say I’m a 50-year-old CFO. Why should my company care about Bitcoin?
Kilian: Because your customers already do. You don’t have to put Bitcoin on your balance sheet, just accept it. Integration expands your customer base and reduces friction. Adding Bitcoin is like adding Alipay to your offering. It significantly expands the user base you can serve.
Look at competitors: in web-hosting or domain markets, an estimated 80% or more already accept Bitcoin. In banking, Swissquote, Sygnum, Amina, and even Zürcher Kantonalbank now offer Bitcoin services. Entering 2025 without it is simply a competitive disadvantage.
And again, you don’t have to hold it. Accept Bitcoin, then instantly convert to whatever currency you prefer.
Janusz: What should decision-makers be cautious about?
Kilian: Compliance. Depending on your jurisdiction, regulation can be the bottleneck.
Janusz: Where is the environment most favorable?
Kilian: EU regulators are usually unfriendly and slow. The UK is open but cautious. Gibraltar and El Salvador are pragmatic. We’re headquartered in El Salvador, they understand what we do and let us operate freely. We also opened an entity in Prospera (Honduras), a Bitcoin-friendly special economic zone.
Boltz’s Clients and Partnerships
Janusz: Who are your clients?
Kilian: Both retail and institutional. Retail users can use Boltz directly via our website. Institutions integrate our API, Aqua Wallet by JAN3 is one example. They handle the UX; we handle the swaps.
Our strength is that our swaps are trustless, we never control customer funds. That’s important for compliance-sensitive partners who don’t want custody risk.
Regional Momentum
Janusz: Which regions do you find most promising now?
Kilian: Latin America. The demand is real. Millions in e.g. Latin America rely on remittances, families sending money from Europe or the U.S. back home. Using Bitcoin or stablecoins like USDT, they can move value faster and cheaper than through Western Union.
That’s not a future scenario, it’s happening right now.
Final Thoughts
Janusz: If you could send one message to builders and executives reading this, what would it be?
Kilian: I’m very bullish on Bitcoin layers and especially on the Lightning Network. It’s time to shine is now, but differently than we first imagined. It’s a professional network, run by professional actors. Companies should embrace that reality: focus on great user experience and let infrastructure like Boltz handle the complexity.
Janusz: Kilian, thank you.
Kilian: Thank you very much.