Ben Carman: LDK Server Release Announcement | Bitcoin 2026

All right, how we doing? Okay. Well, I'm Ben the Carman. I'm an engineer at Spiral. And we've been working on LDK server for the last few months, so I'm going to tell you guys about it. But first, what is LDK? Well, it's just our generic lightning dev kit. The goal is like we have things like LND and CLN and Eclair. These are all just kind of like big packages like monoliths. And they're not very customizable. So and they're you know, they're not written in Rust, which is the greatest language. So we had to make LDK. So it's very customizable where you know, LDK is like ran on large servers and also on like mobile wallets. It even runs in the web. So it kind of supports everything and designed to be like very lightweight and fast. LDK kind of came in late into the lightning scene. So we kind of saw the issues that the other implementations had. So we got to you know, got ahead of that a little bit. And it's ton packed with a ton of features. We um Before we were playing catch-up with all the different protocol changes, but we kind of now have like caught up and done some. So we've just recently released like splicing about 12 stuff. We have all the new stuff like zero fee commitments leveraging the new Bitcoin core mempool rules. We have async payments, which were I think we're the only ones to implement that so far. And then we have built the whole LSPS standard. So all clients and servers have an entire protocol to build LSPs on top of. We have a few integrators with that, but nothing too big. And we've always been mobile first, you know, if we're going to make LDK and lightning and Bitcoin take over the world one day, we all can't have all not going to run servers in our basement. That's kind of a big ask. So we've been very mobile first trying to get this out the door to everyone. And in part of that we is ended up building LDK node. You know, LDK is a really complex API and LDK node simplifies it to make devs easier. And like I said earlier, we have web support. So kind of just runs everywhere and is lightweight as possible. And we've gotten a ton of integrators with this. Most notably like Cash App and Square are probably our biggest integrators. They launched Well, Square launched recently and Cash App's been in there for a few years now. Then we also have big people like Money Dev Kit and Lexi, which are just like Lexi's like a mobile wallet running on SGX. So it's otherwise leveraging the hard stuff of LDK. Money Dev Kit's like a merchant focused one. And we also have like been big integrators like Lightspark. We have the Cashu and Fedimint the e-cash side. Zeus just announced their integration this week. We have Alby as well. So we're kind of getting like you know, whole ecosystem of all these different people using it. So it's you know, LDK is pretty well trusted at these days. We kind of estimate we have about like 25% of the lightning network volume running on LDK. You know, it's kind of impossible to know exact numbers because lightning's privacy guarantees, but from our estimates probably somewhere around there, which is you know, pretty pretty awesome. But the the problem with it is like like I showed earlier, we have all these different integrators, but if someone wants to just use LDK, you have to kind of go use another product that's like custom built to their thing or you have to go build it yourself. So often those like you know, LDK we're marketing to developers not to actually users cuz if it's someone actually wants to use it, it's a go hire a dev or build it yourself. You know, maybe with AI coding it's you know, that's easier, but you know, this is Bitcoin. So it's kind of scary to AI like live code everything. But you know, maybe in a year from now that won't be true, but for now it is. And there's you know, the other out of box tools like LND, CLN, Eclair. All of them and they're all they're all great, but they all have like you know, different quirks and limitations. People often complain about performance with them. They don't have all the features that like they you know, they're missing either like splicing or bolt 12 or whatever new feature you want. And some of them are only built for like end user clients for like you know, Phoenix a lot of people say is like you know, the greatest lightning wallet they have, but you know, you can't like run that on a server really you know, it's only the Eclair is like built for the LSP and then Phoenix is a separate thing. And a lot of them just aren't as customizable as um we would like them to be. They they kind of you know, pick their defaults and their things and you're just stuck using that. And the biggest thing that we think is lacking in the space is LSPs where you know, most of these mobile wallets require an LSP to be able to function. And because of that you need to like go build that LSP, but since this has always been a business venture for these mobile wallets, they always end up closed sourcing that. And at the worst case you know, it's only even for their wallets not even like other wallets could implement their proprietary LSP. So in the meantime we've been developing the LSP spec to try to get that out. So this is why we built LDK server. The idea is to have a you know, high grade high production value LDK node that anyone can run as just a daemon with all these nice features like specifically the LSP support. Um So yeah. We're trying to take everything in LDK and put it in the server. So you'll get all the nice bolt 12, splicing, all that fun stuff in there. You get the zero fee commitments. Everything that's like new in the cutting edge is all going to be baked in and hopefully easily usable to you. We're trying to make it very extensible to anyone. So like like I was saying, you know, we have like people like Cash App and Square and Lightspark all using this on the very high grade production. And we will offer that kind of experience where you know, you can run a billion payments through this. But also LDK's built well for mobile nodes. So you have those same kind of features built into the LDK server, too. So you can run your LDK without a full node or anything. It's just a very very small lightweight server. And you know, we're trying you know, just do all the normal stuff. Well, it's it'll have Docker support, systemd kind of hook-ins, everything to make it easy to to do. And we're very focused on privacy as well getting Tor built in. We have bolt 12 obviously. So just trying to make it usable for everyone and then giving a clean CLI and gRPC. So it's just easiest developer experience possible. And the biggest thing we're trying to do is anyone can be an LSP. That's been like the biggest we found integration like road rough patch to get to new wallets and new mobile clients is just like oh, I want to build a wallet and oh, I got to go find an LSP. An LSP requires you know, $10 million and stuff like that. Plus I have to go build it myself. So hopefully we can kind of get lots of LSPs out there and just really lower that barrier to entry of creating an LSP. And um yeah, we have support for just-in-time channels. I think it's all LSPS 2. We're working on LSPS 5, which allows a lot more dynamic setup. And like I said, we have splicing and stuff integrated now. So LSPS can be a lot more high grade and more capital efficient than they were before. And yeah, we're trying to be enterprise ready. We you know, Cash App and Lightspark they have you know, full developer teams building this lightning infrastructure with LDK and you know, not everyone else can match that. So hopefully LDK server can bridge that gap for people who just want to easy to run high grade lightning nodes. So we're doing some things like Postgres support, Docker, Prometheus. So you can really have all these nice metrics and really watch and duplicate all the data and everything you need to do to keep your LDK node always online. And like I said earlier, you know, LDK is built to like run anywhere. So it's really lightweight. So you can really like you know, build it out correctly where you're you're not you know, just paying a million dollars in server costs. And like I said, all these mobile features are available on the server, too. So you can run a extremely lightweight lightweight node with like no Bitcoin node needed. You can hook it up to like mempool space. We still have like rapid gossip sync. So you don't even need to you know, read all the network graph. And you can use it with an LSP. So you can you know, have your Umbrel or whatever running your LDK server, but you don't need to go worry about oh, where do I open channels to? Where do I do this? Where do do that? It can all be have that you know, same kind of like Phoenix experience, but on your server. So you can like you know, have a little more you know, online guarantees and everything like that. And we're trying to integrate it into everything. You know, in the day of AI live coding, integrations are kind of like you know, three prompts away at most. So we have a MCP server we'll be delivering with it and then we have a skill that we're also developing. So basically just going to have your agent or anything do this. It's pretty fun like my coworker he was using it and just like gave it the whole network graph and was like where should I open a channel? And it just picked some like oh, these are some good channels to open. And it'll all just do it automatically instead of having to like call CLI commands. It's just English. Just making those integrations and testing easier. And we're trying to get this into a bunch of other applications. We I have a PR to to uh ThunderHub to be able to add support to just like traditional existing tools. You can still use them, but with LDK server. We're trying to get into Polar to make easier testing. Um Zeus did announce they're integrating LDK node. And then we're I'm also working on adding a PR to integrate so you can talk remotely to your LDK server. So we're trying to get like all the traditional tools that you use with your existing lightning node will also work with LDK server. And it's ready today mostly, not totally. But we have a preview ready. It's mostly the API is pretty much done. We're just you know, hammering out our latest LDK release and then getting it up up into LDK node and LDK server so everyone can use it. But you know, we want to get people testing today, find some bugs, find some things we're missing, stuff like that. And um we already had a few people point out some stuff in testing. So it's been great. Yeah, if you want to find out about it, we have it's all on GitHub. We have some semblance of docs and then this is all built on top of LDK node and Rust lightning/LDK if you want to check it out as well. Yeah, thank you. >> [music] >> Every year this community comes together to celebrate, to debate, >> [music] >> to build what comes next. And every year >> [music] >> the stage gets bigger. Sound money center [music] stage. So, where do you go to celebrate the next chapter in Bitcoin history? You come home. >> [music] >> Nashville, July 2027.