{ "episodeId": "SLP728", "speakers": { "stephan": { "name": "Stephan Livera", "role": "host", "tag": "STEPHAN" }, "calle": { "name": "Calle", "role": "guest", "tag": "CALLE" } }, "segments": [ { "speaker": "stephan", "time": "00:00", "start": 0.08, "text": "We wanted to see Tap to Pay in Bitcoin. We're all kind of jealous about the fiat payment experience with, you know, you tap your phone and the payment goes through instantly and takes maybe a second or two." }, { "speaker": "calle", "time": "00:11", "start": 10.55, "text": "Hi everyone, and welcome back to Stephan Livera podcast. Today we're re joined by our friend Calle. Calle is known for a bunch of things, probably mostly known for his work on Cashu, but also working on BitChat, and I know, Calle recently put out this new thing. It's called NumoPay, and I wanted to chat about that because I first off, welcome back to the show, Calle." }, { "speaker": "stephan", "time": "00:32", "start": 31.86, "text": "Hey, thanks for having me, Stefan." }, { "speaker": "calle", "time": "00:36", "start": 35.51, "text": "So let's just start with the obvious, like why, why NumoPay? What's the story behind it?" }, { "speaker": "stephan", "time": "00:41", "start": 40.62, "text": "So NumoPay is a payment terminal that we've been working on for quite a while in the background, in stealth mode, in the last, couple months or so, and it's a payment terminal, open source, payment terminal that anyone can download and install on their Android phone, and you can use it to receive Bitcoin in your, your brick and mortar store, basically. And so you can run it on any Android phone out there or on a typical POS device, these open source, open hardware POS devices that are basically everywhere, and, The differentiating factor and the reason why we've been working on NumoPay was because we wanted to see tap-to-pay in Bitcoin. We're all kind of jealous about the fiat payment experience with, you know, you tap your phone and the payment goes through instantly, it takes maybe a second or two, and with Bitcoin, we kind of achieved good UX over the last couple years, but we stagnated a little bit in terms of, you know, we all converged to QR codes and scanning, showing QR codes, and that is- Pretty common in many parts of the world, but all across the world, people are using more and more Tap to Pay using their credit cards, and with NumoPay, that's our approach to bring that kind of experience into the Bitcoin world. And how we were able to achieve this is by leveraging the features or the properties of Cashu itself. So Cashu is a Chaumian eCash system that is built on top of Bitcoin. It kind of gives you a private, instant, cheap way to make Bitcoin payments. Using payment rails that are built on top of Bitcoin, it is a custodial system. That means you have to trust a mint operator with the Bitcoin, when you deposit Bitcoin and receive e-cash for it. The e-cash itself is highly privacy preserving and it's a, it's a bearer asset that you store on the device that you hold it on. So for example, that could be your phone. And because the e-cash is stored on the payer's phone, we can now build these experiences where if you tap that phone onto a- Numo terminal, the e-cash can travel from one phone to another using the NFC chip, and that is exactly kind of the ingredients that you need in order to build this tap-to-pay UX flow for Bitcoin, but now with the twist that we have an open protocol that supports this, it can be built on top of basically anything. Obviously, we choose to build on Bitcoin, and it is highly privacy-preserving. That means kind of We have this rare occurrence where UX and privacy are perfectly aligned, where the best privacy option basically also can give you the best UX option, and I think that that's, that's not typical. Usually you kind of have to make a trade-off between the two, but not in the case of eCash." }, { "speaker": "calle", "time": "03:24", "start": 203.88, "text": "Excellent. And so, yeah, there's a lot in there. We're gonna dive into some of those things, but I guess we'll talk through what it looks like. Now, I had, I just played around with it on my phone. I found it very simple. Basically, I mean, I could probably pull it up just on the screen, but basically, the gist of it is, you download, you install this app, and it, it allows you to very quickly, show a QR. That QR can, you know, show a cashew, basically It looks like, just think you're, think about, you know, you're at the farmer's market, you're the guy selling, you know, meat or whatever, you can, you know, literally type in, I wanna receive whatever one, one thousand, one hundred sat or whatever it is, and just, it shows a QR. The, I guess to your point, Calle, the difference is here you can also, not just scan to pay like we're used to in Bitcoin with Lightning, but you can also tap to pay. So just elaborate a little bit on what" }, { "speaker": "stephan", "time": "04:20", "start": 259.65, "text": "Yeah, so the setup is extremely easy. You download the app, you install it, and during the setup process, that's it. You don't need any additional software, you don't need to run a server somewhere in the cloud, you don't need to get a VPS or anything. So that was very important for us, that the, the setup is super seamless. The only thing that you need to decide at the beginning, and we help you with that, is to choose a mint. That means where the Bitcoin is going to flow into, and then you can withdraw it from there. So once" }, { "speaker": "stephan", "time": "04:49", "start": 289.33, "text": "We're showing it into the camera, basically a super simple checkout POS flow where you enter the amount. And as you said, you're then, you know, once you enter the amount, you see a QR code, and there are two QR codes there. First of all, there's a Cashu QR code, which is a Cashu payment request, and you can also flip on Lightning, and we, we do both. Basically, it can-- it supports Cashu payments directly or Lightning payments for everyone else who doesn't have a Cashu wallet yet. So, it presents you both, and With the camera, but on top of that, there's also the tap-to-pay experience that we've implemented for both Cashu and Lightning. So that means in the case of Cashu, if you have a Cashu wallet and your customer has a Cashu wallet, they, instead of scanning the QR code, they can just tap their phone onto your phone and their Cashu wallet will automatically detect that this is a Cashu payment request and then select some e-cash from their device and send it over via NFC to the receiver's POS device. So that is a purely- The offline payment. Your, customer's phone doesn't really, doesn't even need to be online for it, as long as there's some eCash in the phone, the eCash will travel directly from, from one phone to the other without even touching the internet. And that has a couple of very cool- Features or, you know, gives-- first of all, it is instant, so you don't have this delay that you need to connect to the internet. Second of all, it, it is independent of internet connectivity, so it always works as long as the POS device, the receiver has internet, the customer will always be able to, to pay, and that is also the case for credit card tap-to-pay, by the way. And third of all, because you don't touch the internet, and, you know, coupled with the incredible privacy that eCash- Already gives you, and you don't even touch the internet, that means you have kind of like twice the amount of privacy even if you want, because your device doesn't even register, you know, on any server that it's making this payment right now. The only thing that the mint sees is that the receiver POS has done a swap, so that eCash came in and eCash went out, kind of like the receiver takes the eCash, swaps it with the mint for new eCash, and that's it. The mint doesn't see, whether there was a sale, who paid for it And like any other personal information of the payers. And so I was saying there's this e-cash part, there's also the Lightning part. So for anyone with just a Lightning wallet, they can still pay at any Numo terminal because we create invoices automatically. There's also a, kind of, Phoenix is the only wallet that supports this, there's also a push to support Tap to Pay with Lightning. So what, what your terminal does is basically it, it offers the Lightning invoice via NFC. So any device that can read NFC from the device and, that could be a, a Phoenix wallet, for example, can read that Bolt 11 invoice and then make a payment over the internet to the terminal using Lightning. Unfortunately So so far, I'm only aware of Phoenix really supporting this, and there's definitely more interest in the ecosystem. This is also our goal to increase interest in Tap to Pay and hope that more wallets, will follow up and follow soon and integrate Tap to Pay into, their wallets as well, especially if it's just Lightning wallets. Obviously, we have, I think eight or so Cash wallets to support this out of the box right away. So we hope that we'll see also more penetration in Lightning for this kind of Payment experience, and we're also pushing for, for the adoption of a Bib, that's Bib three two one. I think at least that's unified QR codes. Someone needs to correct me on the Bib number, but unified QR codes or unified payment, unified payment addresses are a way for, for a Bitcoin wallet to offer you, for example, if you wanna pay to it, an on-chain address, a Bolt eleven address, and also now a Cashu payment request, all in a single QR code, all in a single In one, payload. And so for QR codes, this was kind of a problem because the QR code used to get larger and larger, which makes scanning harder and harder. But for NFC, this is really ideal because for NFC, you don't really care about the payload size that much. It will, it will work. So you just tap to, tap your phone to the POS device, and it could receive like this BIP unified QR code payload, and then the wallet itself could decide, \"I'm an on- Chain wallet, so I'll pay in on-chain. I'm a Lightning wallet, so I'll pay with Lightning, or I'm a cash wallet, so I'll pay with cash. And so we're, we're trying to kind of raise the bar in the expectation of what good UX should look like and hope that everyone else will also see this and will see more and more adoption of Tap to Pay in Bitcoin." }, { "speaker": "calle", "time": "09:42", "start": 581.92, "text": "Yeah. And I just quickly check, just for listeners, it is BIP three two one, came out in November twenty twenty-four, looks like it's by Matt Corallo, relating to the URI scheme, and it's kind of like an advanced, or maybe an update or a kind of a upgrade to BIP twenty-one, which some listeners may know, historically, which was similarly about unified QR codes. The other big thing that we should mention for listeners, Calle, if you can explain this idea of order withdrawing to a Lightning address, 'cause I think that's also The common fear people may have is, \"Look, what if I get rugged by this mint? Well, now it's gonna be a different context or it's gonna work in a different way.\" Can you explain the rationale and how this works in NumoPay?" }, { "speaker": "stephan", "time": "10:23", "start": 622.72, "text": "Yeah, absolutely. So the eCash that you re-receive as a POS device, as a Numo POS, lives on the, on the device itself. And as we said before, Cashew is a custodial system, so as a user of Cashew, you want to limit your ex-risk Exposure risk to this custodial risk of the mint operator. Obviously, this, the mint itself could be operated by, let's say, the restaurant owner themselves, so you don't really have this, trust issue there, because the, the payment infrastructure itself could be run by the same people that also use the POS. But in general, this won't be true. There will be many more people who just wanna use the POS and fewer people who will run the infrastructure, right? So there's this risk scenario. And again, as I said, the eCash itself lives on the device, so Also means, you know, although you have a seed phrase and you can back up everything, you, you eventually want to withdraw the funds from the POS to some other centralized place where, for example, you have a restaurant, you have a single big wallet where all the, payments should flow in, so you wanna handle, you know, your ten different POS devices, they should all, withdraw to the same address. That's, that's kind of the goal. So for this, we have built in the auto withdrawal with Lightning address Yes. And what this looks like is very simple. When you set up the wallet, you can go into the settings and you say, \"Enable auto withdrawal,\" and then you can set a threshold, an amount threshold. For example, it could be fifty thousand satoshis, and, and enter a Lightning address from your non-custodial Lightning node or any other wallet that provides you a Lightning address. And with that, you basically have everything. Now you can give this POS to your, let's say, your workforce and your, you know People working in your store, for example, and they could collect payments for all the things that they sell over the, during the day, and as soon as the wallet reaches that threshold that you've set, so the balance of the wallet, the POS reaches, let's say, fifty thousand sat, it will automatically execute a withdrawal to the lightning address that you've set so that the exposure risk per device can be perfectly controlled and kept in a safe range, basically. So that way you can make, you know, hundreds of thousands of sat per day without risking too much to either the individual POS devices being lost or being stolen or something like that, or the mint operator who could, rug you anytime by turning off the mint." }, { "speaker": "calle", "time": "12:50", "start": 769.85, "text": "Yeah, it's a fascinating, and it's just really interesting to see how quickly these ideas are kind of all evolving now. Like if I think back to earlier years, in order to do this, people had to use BTC Pay Server and set it all up that way and have, you know, a quite an involved setup, or maybe they had just like one guy with an app kind of thing. But then when you go to the shop, that guy has to be there and know how to use it, otherwise you can't pay. Whereas now it's like there are all these ways that people can just have withdrawn, let's say, to the owner's, the merchant's Lightning address, or even if he needs-- let's say he's a restaurant owner, he needs to send it to his Lightning address that's on an exchange, 'cause he has to sell some for fiat. Like it can just be kind of automatically, programmatically done. And so that's like, it's just enabling all these new things that allow, obviously, people to use Bitcoin peer to peer. So I think it's a really fascinating and a really, just kind of an interesting evolution that we're seeing. Now, Different options now, aren't they?" }, { "speaker": "stephan", "time": "13:51", "start": 830.95, "text": "No, that, that's, that's the most important thing, and it's, it's good that we have a diversity of options. There will be a solution for every skill level, knowledge level, how deep you are already in the tech, obviously. But the biggest blocking factor for Bitcoin today, I think, is not kind of the existence of the tech, it's more the UX side and kind of convincing people to stay on board. And I've noticed or experienced this multiple times myself that I go into a store, as you said, there's like, there's the Bitcoin, Bitcoin enthusiast owner of the store who set up a POS device like months ago, and then as other workers join or, you know, another cashier works at the, at the counter today, and they might not know how to use Bitcoin, and so on that day you can't pay with Bitcoin, but you have to come back when the owner is back in the store, then you can pay with Bitcoin. Like I've experienced exactly this, this scenario many times before. So this- This shows you what the real problem is. It's not that Bitcoin is off on every Thursday so you can't buy, pay with Bitcoin anymore, it's because the workers themselves haven't learned how to use the device, although it could be very easy or someone could show them. So we just wanna, lower the bar that makes Bitcoin useful for people and, and in fiat, and you can see how much work has gone into making sure that fiat is as seamless and simple as possible. So this is what credit card experiences today mimic. It's basically, you know, no thinking, you just take out your phone, in most phones you don't even need to unlock your phone anymore to pay, you just hold it to the device and it's done. You don't need to, use your fingerprint or anything. They have like thresholds for small payments where you don't even need to confirm anything. So, and, and obviously the POS market for fiat is well established and, and, has lots of different options for people to use. And In Bitcoin, we haven't seen that much of a push in that realm with super simple UX yet. So most of the solutions either, you know, require you to understand how Bitcoin works, which is a big problem for, for, you know, all these people who are not Bitcoiners but are supposed to use Bitcoin in the store when they, when they work in there, or set and run and manage your own infrastructure, which is something that, you know, I can do no problem, but I know that ninety-eight percent of people won't. Won't be able to achieve that kind of knowledge because they wanna focus on something else, they wanna run a business, they don't wanna take care of the POS, infrastructure to actually do their business. So I think as a developer community in Bitcoin, we need to be much more thoughtful about what, you know Where our users are and who we want to, to actually use our software. If we just build software for each other, for all the nerds and all the people who are really deep into Bitcoin, that will just limit the way that Bitcoin can grow, whereas other payment rails, especially fiat and stablecoins are really pushing super hard to make their, their experience as seamless and intuitive and simple as possible." }, { "speaker": "calle", "time": "17:03", "start": 1022.71, "text": "There has been a massive investment in making these things as slick as possible, because hey, they wanna get, they wanna make sure they can take payment in a slick way, and of course, it's like the fiat payment rails, what we're starting to see in a lot of places now, and especially kind of post all the lockdown era, we're starting to see when you go to a restaurant, it's, you scan the QR to see the menu. And nowadays, it's quite common, I mean, even for me, I, I live in Dubai, I live in the UAE, we go to That, and again, it's a fiat payment, and it might be like Google Pay or something like this, or typing in your mat-- your credit card details. But that's, that's the direction things are going. And so if we can't get Bitcoin and Lightning payments built in to that, it's, it's just gonna be a very difficult uphill battle." }, { "speaker": "stephan", "time": "17:50", "start": 1069.96, "text": "Yeah, it's, it's getting harder and harder to catch up, which isn't the situation that we wanna be in. We, you know, the Bitcoin gave us the possibility to build payment systems outside of this, fiat system, which, where you have huge companies pushing for adoption, and they have been lagging behind for years before. If you think back ten years or so, fiat payments still sucked on the internet. There was kind of only PayPal and, you know, Google Pay, Apple Pay, all those weren't, you know, either not around or not pop- or not really popular. Especially the situation that you just, painted, where you use a web checkout in the restaurant, although you're physically present, the web checkout itself is more efficient because you don't need to get up, stand in line, there isn't no, you know, no, no, no, a worker doesn't need to take care of you, you just, you do everything on your table and you finish the job on your table, you go out. That is an efficiency gain, and that is also why th- these technologies spread, because the more efficient, the easier, the less manual work Work is necessary to achieve a goal that is typically something that, you know, gains popularity and is being pushed. These companies obviously have financial incentives to push these technologies because they also make a profit from seeing it being adopted. There's no issue with that, it's just like an additional incentive. Whereas in Bitcoin, our incentive is mostly, you know, we, we work in open source, we collaborate across different projects because we have all a singular goal which is to push Bitcoin adoption. And so that also means that we, it requires A bit more coordination and working together in pushing it into the same direction. That is also why, you know, Bibs like Bib three two one exists because we want a unified experience that everyone can adopt so we can all march forward together. Sometimes that's a bit slower, but I believe that is longer lasting. We have a better foundation to build on, and because I know that we'll be working and improving Bitcoin over decades and decades to come, I'm pretty confident And that we will be able, you know, to, to, make that gap between Bitcoin experiences and fiat experiences narrower and smaller over time." }, { "speaker": "calle", "time": "20:08", "start": 1207.81, "text": "So if I were to think about, if I were to ask you, where are you going with NumoPay in the future? Like, what kinds of features or direction are you going to take that project?" }, { "speaker": "stephan", "time": "20:19", "start": 1218.67, "text": "So it, it is fully open source and it's free, and anyone can download it, modify it, use it as they like. it is built on top of the Cashu protocol, and, so it gives you as an operator many different options to actually deploy it and, and experiment with it. We are working on a BTC Pay server integration as well, so we want to be able to not only use, a Cashu Mint as a backend, but also a BTC Pay server as a backend, because the u- UI and the UX that we've built is super slick. It can be also useful for other Bitcoin projects. Numo, for example, has a, tipping feature where the customer can leave a tip to the, to the worker. It has a basket feature where you have-- you can manage multiple, let's say, tables in a restaurant and then, you know, add items and check out later. a, receipt feature where you can print out receipts that you can give to your customers. So there's a bunch of, really useful features that we've- Thought hard about and we've, you know, considered what is necessary for a good experience in a store when you actually work there. And so all of these features, we also want to be able to provide to other platforms. So we're working on a BTC Pay server integration that is already working, it's just not released yet, but it's open source, you can find it online if you look for it. And we also have a dashboard in the works where a single computer, let's say in the store, you can observe the activity of all the Numo terminals in your store. So let's say you have five of these terminals that you give to your workers, then a single place where you can, you know, there will be a single place where you can see how many items are sold across all the devices, who has made how much money, and time series and, and so on and so forth. So working on more analyticals, analytics software to make operations easier and improve integrations with existing Bitcoin wallets. As I said, also we're also pushing, the adoption of the three to one So we want more unified, payment payloads, unified QR codes across the space, and I just wanna be contributing towards our larger goal, and that is our north star goal, is to push Bitcoin as money and as push the adoption of Bitcoin as a payment system. That is the most important thing for us, and it's kind of, the highest reason, the biggest reason why we work on Cashu and why we, put out NumoPay." }, { "speaker": "calle", "time": "22:46", "start": 1366.46, "text": "Excellent. And so with Cashu, just kind of more generally, give us a bit of an overview on where the ecosystem is at nowadays. Like as I understand, I mean, there's a bunch of people running the underlying mints, there are a range of Cashu wallets, you're trying to show ways that it can be built, obviously with NumoPay, that it can be like a merchant tool. Give us an overview, where is the Cashu ecosystem at nowadays?" }, { "speaker": "stephan", "time": "23:09", "start": 1388.85, "text": "So the project itself has been around for, I think around three years now, and in that time we've seen quite, astonishing growth. we started with just a very few projects at the beginning, was just me and another guy who joined, and we've been building all, wallets and software. At some point it became a protocol, so we kind of intentionally tear down everything and rebuild everything as a specification with documents where everything is documented So anyone else can also join the protocol and build their own software, and we've succeeded with that, to date. I-- it's really hard to even keep track of it. There is a awesome cashew repository on GitHub where we're trying to collect all the different projects that we encounter, but, there are dozens of different wallets that are being maintained, built by different, projects, and there are, you know Maybe somewhere between fifty and a hundred mints that I've-- I was able to find, that are running and operating from small size to bigger size, from, you know, personal mints for a single family to, large mint of, regulated company. So there's the whole bandwidth of, individual tinkerers and hackers to actual serious company deployments where people even make money by running infrastructure. so the, the, there's been a astonishing adoption across the board for Bitcoin payment systems, and then there's kind of an, a completely separate layer of users or, or consumers of Cashu, which just basically focuses on the token and bearer asset nature of eCash itself, and that was also one of the goals when we built the protocol, is to show and make it easy and possible for everyone to just use the eCash Cash part without having to hook it up or connect it to a monetary base system. And so you can just use the eCash without Bitcoin. And so projects like Tollgate come to mind where they, they literally sell not Satoshi eCash tokens, but denominated in megabytes for a internet router. So it's like a community internet router where you can become an ISP yourself, and you can sell internet access to your router to your neighborhood, for example. And And so they use Cashu in order to coordinate the payments in the system, or you could call it credits for using the system. Another project that I, that I'm thinking of is Portal, for example Portal is a new Bitcoin, inspired, kind of a wallet and identity management app, and they're partnering also with a Bitcoin conference in this year, where they are selling the tickets as Cash App tokens. So you will have kind of privacy-preserving tickets for a conference, for a Bitcoin conference that, cannot be double-spent, so you can also sell them or give them to someone else. It's a big problem in the ticketing world is double spending, because, you know, when you go online and you buy a ticket Which is just a PDF file, for example. How do you know that the same ticket hasn't been sold to three other people, right? So there's no way to verify that. With eCash, it's just a simple transfer of that token from one person to another, and then the ticket is transferred. Even, you know, the nice part about it is that you have perfect privacy, the operator of that conference doesn't know who bought which ticket. So there's a lot of adoption in Bitcoin. Everyone is talking about Cashu. I go to conferences, there's always a Cashu talk. There dozens and dozens of people working on the Cashu main protocol, probably hundreds of people working around Cashu or with Cashu. So in that sense, it's a great success and, a fundamental part now of the Bitcoin ecosystem, at least that's how I perceive it and that's how, I see activity in conferences and so on. And then there is like this, this interesting experimental adoption that basically just uses the eCash part itself and tries to- Improve the privacy and properties of other non-monetary systems such as internet use, ticketing, and, and so many more." }, { "speaker": "calle", "time": "27:28", "start": 1648.5, "text": "Yeah, it's fascinating because I think it's, there's, it's, it's grown so quickly. If- Okay, let's put it this way. Where do you think people should be using a cashew system where they are currently not using it, especially in like web or corporate like environments? I think that, that would be useful for listeners." }, { "speaker": "stephan", "time": "27:49", "start": 1669.04, "text": "So Cashu isn't a replacement for non-custodial systems, because you, you don't hold the keys for the Bitcoin that is denominated with Cashu in most cases. So how we see Cashu, play a role is to improve existing custodial systems of which there are tons and tons around. We want to improve, first of all, the ability to run these systems on yourself, so you don't have to rely on a third party operator company that runs Let's say, you know, wallet of Satoshi or something, or an exchange like Kraken or anything where your Bitcoin isn't secured by yourself, that's where Cashu comes in. So you can run the mint yourself, and all the users of the, of those s-systems, their privacy is like greatly enhanced. I wanna say the best possible privacy that you can get with, with any type of cryptocurrency used today is probably, is using eCash. So that's why we're so passionate About it, because it allows you as a user to be uncensorable and untrackable even when you're using a custodial system. So in that lo-in that sense, it's a big level up. And for the organizational case, we've seen interest from people expressing their needs about internal organizational funds. So there's like cross- Cross company payments, if you have a multinational, for example, where, there's, there's one project where someone told me about this idea, is they wanna set up a mint for their multinational organization because they have this big problem of sending funds around internally and making sure that everything is accounted for internally. And for internal payments, it's perfect because you could set up a mint for your internal organiz-- for your, for your international organization and then, then send around funds between different branches Of that organization, for example, as eCash, and you don't need to account for it because the eCash itself is already-- the flow of eCash itself is basically accounted for. There is no double spending risk as long as you, receive the funds, you know that the receiver has them, and you don't need to make sure that you keep track, of all the payments in a ledger, for example. For-- and another thing where people are interested in is a payout of salaries within an organization, so you know that you're paying your- Your, your employees, let's say, you know, I don't know, a hundred K per month or something, and that's, that's the total sum of the salaries that you pay out, and maybe you don't wanna know what their on-chain address is and what their node, public key is, the lightning node public key. So if you want to preserve Privacy and anonymity within your organization, it is also useful for that because you could, in that case, just pay your employees in eCash and let them withdraw it to their, Lightning node, to their, Bitcoin on-chain address without having to keep track of who has which address." }, { "speaker": "calle", "time": "30:48", "start": 1848.1, "text": "Yeah, so it's just interesting to point out that there are these scenarios where it could be used now to provide more privacy because sometimes in, you know, even in quote-unquote crypto world, they all sometimes attack Bitcoin and say, \"Oh, Bitcoin's...\" It's not private while neglecting some of these privacy techniques that can be used in, that already can be used in Bitcoin, obviously things like Payjoin, silent payments, Lightning, and as you mentioned, Cashu, because these all combined can actually provide privacy, but it's just more like the world today hasn't quite set up to use that, right? So for example, if exchanges started to use Payjoin, if more people had, you know, Lightning uses instead of defaulting to just doing things on chain With the static donation address, if we started to use like that kind of best, the best that's available already today, Silent Payments, Payjoin, Lightning, Cashu, some combination of these things, we actually would have some level of privacy in our Bitcoin use." }, { "speaker": "stephan", "time": "31:46", "start": 1905.7, "text": "Yes. So as a advanced user of Bitcoin, you can achieve great levels of privacy already today with all the tools that you've mentioned, but here's-- that is, you know, it's related to the point that we were making earlier is the UX- Of these individual privacy methods really plays an important role in the adoption. So I believe that privacy needs to be a default, and you, you shouldn't have to decide or research or figure out how to improve your privacy if you want everyone to use it. So we should be working on, on solutions where the user even doesn't need to care whether it's a private- Method or not, they should be just basically thrown into a privacy preserving system by default, and that's why also using privacy preserving systems must be as smooth as using any other system out there, because it just requires too much effort for most users to even climb over that hill. And, you know, it's not in everyone's interest to be perfectly private, because most people don't even know what the risks are, so why should they care about being private? And that's- That's what you will hear when you have these conversations with normies, they will say like, \"I have nothing to hide,\" is the most common thing that most people say. Obviously, you don't have anything to hide until it's too late. So we, and the other part is that the more people use privacy-preserving systems, the better for everyone else, because privacy lives of numbers. That the more people are part of an anonymity set, the better for everyone inside that anonymity set. And that is why UX is so fundamentally important. It is, it is almost as- is important or maybe even more important than the actual technical solution to the problem itself, because if it's too hard, then it will only reach a very limited number of people. And for privacy, that is a fundamental lose. For privacy, we fundamentally want everyone to use it. So we just have to be a lot more cognizant about, about these trade-offs and how real people with, you know, completely different goals than you Should be using these technologies as well. As I said before, the shop owner probably doesn't care about privacy, but cares about their sales, right? And that is what they should care about. But we, we can give them solutions that have incredible privacy built in, even without having to make that cognitive decision themselves." }, { "speaker": "calle", "time": "34:22", "start": 2061.66, "text": "The other topic that I know is obviously very relevant nowadays with AI, vibe coding, and so on. I know you're working on a bunch of different projects. And I know you are also using a lot of this AI, tooling to amplify your productivity. So can you give us some thoughts, where are you at on, the use of AI, vibe coding, and, these tools to, be more productive?" }, { "speaker": "stephan", "time": "34:45", "start": 2084.92, "text": "Yeah, so, I, I, I hope that there's probably no developer out there anymore who hasn't already, you know, figured that, that things are fundamentally changing and, and especially for developers. Everything has changed in, in the last year or two maximum, although, you know, the development of AI and the evolution of AI models has been a much longer story, the penetration into the actual productive world Has maybe started to materialize in one or two years ago, and, it seems like in the last six months it is really picking up and at this point Everyone is understanding that software development will never go back to what it was before. And, so I'm talking about AI assisted, assisted coding or agent coding or web coding in where you, instead of writing most of your code manually, you let an AI agent to write the code, and what you do as a software developer is you describe your intent or the goals that you wanna reach to the machine, and, you do that in a way That you expect the machine to understand you in the best way, and then the machine executes and you review the code or you accept, accept whatever the machine does or not. And, so the flow or the method of how we're writing software has fundamentally changed, and, and with that, the, productivity and the output that a single motivated person can produce has increased by many folds and within a very short period of time. Personally, I would have never thought that I would ever witness this in the course of my lifetime, because although I've been following AI developments for Very long time, very closely and seeing this happen in real time with every single model along the way, and even, you know, before GPT and everything was around, where people have been already demonstrating that these models can produce text really well, it wasn't clear really that they will also be able to produce really good code. And even I, so deep I would consider my, myself so deep into the space, didn't expect a year ago that, we will come to a point that fast, that quickly, where, you, you don't even really have to look at the code that much anymore, and you as a professional developer will Most of the time, not be able to produce better code than the machine itself. So like one year ago, my conversations with, developers were often along the lines of, you know, hey, are you using these tools? And if you do, if you don't do, why not? And the answers that I would get most of the times were that these agents are still too bad, they make mistakes, they're not good enough for my expectation, and that's why, I'm not using them. And within a single year, that, that has completely changed. They were So there are still people who are incredibly good at what they're doing and AI agents won't be able to match them yet. Obviously, they will be able to match them soon because that's the only direction that we're, that we've been moving towards. But the-- for most developers, and it's probably like above ninety-five percent of developers, AI agents today produce already better code, than them, and they're not only producing better code, but they're also producing it a hundred times faster than any developer can do. So, you, if you're a developer Then it's, it's almost already, you know, you're already too late if you haven't adopted this, but you still have a chance. You, you still have a chance to save yourself because the output efficiency that you gain from using these tools correctly is just mind-blowing. And it's, it's hard to compare to anything else because I really can't compare to anything else. Maybe, you know, the horse buggy against the car even, but not even that makes, you know, that much of a jump. But that, not even that was like a ten to twenty x improvement. It's like the difference" }, { "speaker": "calle", "time": "38:58", "start": 2338.25, "text": "between walking and driving." }, { "speaker": "stephan", "time": "39:01", "start": 2340.58, "text": "It's, it, yes, probably, but it, it's probably that, but, you know, there's even with walking, you can get to places where you can't go with driving. You'd just be slower, but you will get there. With AI tooling and agents, you can get to places where you will never be able to go as a person. Right. And because it can learn things as well. Yes." }, { "speaker": "calle", "time": "39:23", "start": 2362.65, "text": "So it knows the things that you don't know. Maybe. Yeah. So can you, for listeners who are interested, maybe the developers or builders themselves, do you have Do you have any tips on the best ways to leverage this AI or leverage AI tools? What tools are you using? Any tips for listeners who wanna build Bitcoin stuff with AI?" }, { "speaker": "stephan", "time": "39:39", "start": 2379.44, "text": "Yeah, so whatever I say right now, will be obsolete in two months, so I won't be able-- won't give you like specific tips. Or maybe, you know, I can tell you what my pipeline is today, but I use all the models. I don't care about which models it is, I just switch around. You need to figure out which model is good at what, right? That is And you use a coding agent, there's, there's kind of a harness that, that, that contains the brain, which is the AI model, and gives it legs and arms, which is reading files, writing files, searching the web, and, and doing kind of actions in the real world. I heavily use Open Code today. I also use Goose from time to time, and I use other agents, Codex and Claude Code and all of these different things as well. So my tip to developers is, first of all, if you, if you haven't tried it yet, then, Time now, you need to start learning these things, and then you need to keep learning, in the next, for the next couple years, maybe less than that, your job is basically staying on top of this technology because it's changing so fast that things that I've been doing, that I was doing six months ago, I don't do anymore. I just try to, whenever there is a new release of something new, fundamental, fundamentally new, I try to get on top of it as quickly as I can because I know that there's a bunch of people doing exactly the same thing, and I useful for me or not, whether I can ignore it or whether I should invest more time in figuring it out. So right now, I think we're in kind of the most turbulent of times, which is, you know, the, the ecosystem will settle in six to twelve months to some, you know, specific form of using these tools. But right now, anything that is out there could be kind of revolutionary and new. So what you should be doing is to invest more time in learning to use these tools and understanding what these different tools are, how they're built. And, how you can make use of them. That's the, that's the thing to focus on right now, is try everything, figure out what works for you, and keep trying until this, this transformation has settled." }, { "speaker": "calle", "time": "41:42", "start": 2502.27, "text": "Yeah, it's a, it's a really very quickly changing time, right? I think a few years ago, it was almost like you really had to have something to be a programmer, you sort of had to think a certain way to do it, whereas now it's almost like it's just opened up the access so much more that now you can learn and do things that previously, you know, it's like, it's like, you know, previously you were handicapped, but now with AI tools, you're not handicapped, you can think better or learn faster. So really fascinating times. I think we'll leave it there though, but listeners, make sure you check it out. As, as Calle said, it's a really slick UX. I was playing around with it, like if you have, you know, family or friends who are looking at, you know, could benefit from using Bitcoin payments, check out NumoPay. I think the UX is really, really slick. It's very like, just click, simple, you know, a very guided process, very similar UX that, you know, normies will be used to from their fiat perspective." }, { "speaker": "stephan", "time": "42:39", "start": 2558.62, "text": "So for NumoPay, you can go to numo-pay dot org. It's fully free and open source, download it and try it out. you need a Android device to receive, but any iOS and Android app can pay to it, so that's NumoPay. you can find me on socials where you'll probably see me should posting somewhere, so I'm not gonna have to point, you towards my profile, I will find you. And if you're a developer out there who's kind of, looking for a purpose and figuring out what to do in" }, { "speaker": "stephan", "time": "43:09", "start": 2588.58, "text": "So consider joining the Bitcoin open source development space. We are working as a very large group of people all around the world with, strong purpose, into a singular direction which is pushing Bitcoin as a global monetary system on the internet. We need your help. We need more people working on open source Bitcoin tech The, the, we are the fundamental kind of building, the fundamental layer of making sure that Bitcoin will prevail in the next ten, twenty, thirty, two hundred years. So please join us and reconsider if your job is boring and you work in a stupid tech startup that you never supported, then just quit, start contributing to Bitcoin, look for grants, look for companies that can help you support that, and, and join us." }, { "speaker": "calle", "time": "43:58", "start": 2638.0, "text": "Fantastic, thank you, Calle." } ] }