Launching Boltz Client 🚀

Today we are excited to launch Boltz Client, a swap client for Lightning node runners that connects to CLN or LND nodes and allows for automated, unfairly cheap channel rebalancing

For those short on time, here's a quick overview of the key features of Boltz Client:

• ⚡ CLN-first: first-class citizen support for CLN in addition to LND

• 🌊 Liquid-first: optimized UX for channel rebalancing using Liquid swaps

• 🥕 Taproot-first: full support of Taproot Swaps and Boltz API v2

• 👛 Integrated Liquid & mainchain wallets: create, import & swap to cold wallets

• 🤖 Autoswap: fine-grained control for automated channel rebalancing

• ⬆️ Backward compatible: Upgrade from Boltz LND

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What is Boltz Client?

History

Boltz Client is based on Boltz LND and written in go. Boltz LND was our go-to swap client for LND runners est 2020. It was built for a very simple purpose: let LND runners swap between Lightning and the Bitcoin mainchain on demand to rebalance channels.

First Boltz LND release from 2020

Initially, Boltz LND was a standalone CLI-based client, but later it was integrated in UI-based tools like the popular Ride The Lightning node management software.

We estimate Boltz LND to be running on 1k+ Lightning nodes today. All these will be able to seamlessly upgrade to Boltz Client in the coming weeks.

CLN & The Path to Multi-Implementation

With CLN gaining popularity for its focus on performance and stability, along with the support in popular lightning tooling, we are excited to add Boltz Client to the growing CLN ecosystem today. Boltz Client uses CLN’s gRPC (missing calls were swiftly added by the CLN team 🙌), and the upcoming 0.15.1 release of Ride The Lightning will fully support Boltz Swaps for CLN nodes through its UI. This lays the foundation for integration of more Lightning implementations in the future.

Boltz Swaps in upcoming Ride The Lightning release with CLN

Liquid & Taproot

Boltz Client ships with full support of Liquid & Taproot Swaps and the brand-new Boltz API v2. This means all Taproot Swaps-inherited features like immediate cooperative refunds, increased swap reliability, cheaper network fees & increased privacy are directly available in Boltz Client from the get-go.

Also, Boltz Client brings its own wallet system for Liquid and the Bitcoin mainchain, powered by Blockstream’s GDK. This gives users an extensive set of options:

• Use the connected Lightning node’s internal wallet for mainchain swaps

• Import an existing Liquid/mainchain wallet seed, e.g. from Blockstream Green

• Create a new Liquid/mainchain wallet

• Import a cold wallet xpub/descriptor as swap destination

• Swap from/to external addresses

A very nice side-effect of the integrated wallet system is that Boltz Client can automate refunds for Chain → Lightning swaps now, as it has access to wallets to pull addresses for refunds. Automating refunds is the last missing piece for a polished UX of Boltz Swaps: if something goes wrong, funds return automatically and immediately.

Autoswap

The flagship feature of Boltz Client is called Autoswap. As the name suggests, it let’s Lightning node runners set up a configuration for which swaps will be performed automatically to keep channels balanced:

Liquid wallet selection in Autoswap setup via boltzcli

Autoswap setup guides through the major configuration options

In the basic example above, we instructed Autoswap to rebalance our total channel balances to 37.5% outbound with a maximum total of 100k sats to be spent on fees within 7 days if our total outbound capacity exceeds 75%.

Download

Today we are making Boltz Client available to the general public. Big shout-out to our newest team member Jackstar who brought Boltz Client to life 👊

Docs are available here and you can grab the latest release 👉 here 👈 !

What's Next

• Release full CLN support for Boltz Swaps in RTL, deploy to Umbrel, Start9 etc.

• Taproot-based L-BTC/BTC ⛓️-to-⛓️ swaps, which will allow Autoswap to unleash Liquid’s full potential for channel rebalancing by periodically moving funds back to the Bitcoin mainchain either based on amount accumulated in Liquid or based on the current Bitcoin mainchain miner fee level.

• A UI. We are aware that, while powerful, CLI is not for everyone. That’s why we started working on a native UI for Boltz Client with a tailored UX for rebalancing nodes and controlling Autoswap.

  

  PoC of a Web App build connected to Boltz Client

We’d love to hear from you!

We acknowledge that perfection is elusive, and Boltz Client is no exception. We value your feedback, bug reports, and feature requests, which can be shared through GitHub, X, Nostr, or our Discord server!