Company Name: Ark Labs

Founders: Marco Argentieri and Simone Giacomelli

Date Founded: June 2024

Location of Headquarters: Europe

Number of Employees: Six full time

Website: https://arklabs.to/

Public or Private? Private

Ten years ago, just after graduating from high school, Marco Argentieri began his career in Bitcoin.

Some of his earliest work in the industry included helping people make remittance payments using bitcoin. From those early days, Argentieri looked at bitcoin more like a currency and less like an investment, and he helped to make it easier for others to use.

“I had many people that were using Bitcoin because it was like a Western Union without the KYC hurdles, and it was much cheaper back then,” Argentieri told Bitcoin Magazine.

“They were not even interested in bitcoin price or volatility. They were just using it to send money overseas,” he added.

Fast forward to 2024, and Argentieri is still focused on the same mission: helping people to use bitcoin cheaply, easily and privately. Though these days he does this in a more sophisticated way via his company Ark Labs, through which Argentieri and his team develop the Bitcoin layer 2 Ark.

What is Ark?

Ark is an open-source protocol created to help scale Bitcoin. The protocol enables users to amortize the cost of a single on-chain transaction across many off-chain swaps. These swaps occur on Ark’s servers, and they’re most well-suited for Bitcoin users who already operate Lightning nodes.

Ark servers were created to remedy the liquidity constraints of Lightning by allowing users to receive funds off-chain in what are called vTXOs (Virtual Transaction Outputs), which alleviates the need to open a channel and/or receive inbound liquidity. The off-chain system runs on Ark servers, which also enable unilateral withdrawals on-chain.

Ark provides and sources the liquidity for the transactions it facilitates via its servers (instead of relying on peers for liquidity the way that Lightning does). Argentieri embraced Ark as a solution after acknowledging Lightning’s shortcomings.

“Looking at a current scaling solution like Lightning, the developers were idealistic in the sense that they were saying ‘Okay, people should hold the keys, which is a big, big, big step. And plus they also run server and plus they also became very expert in liquidity management and whatnot,” explained Argentieri. “I think that hasn’t been a very realistic assumption for how people operate.”

Argentieri founded Ark Labs under the pretext that just as most people didn’t want to deal with using bitcoin on their own for remittance payments 10 years ago, they don’t want to become experts in running Lightning nodes to make payment these days.

“Ark tries to build on top of this assumption that there will be specialized people or specialized enterprises that know how to handle liquidity, and that’s what we call Ark servers,” he explained.

“Then you have like the clients — people that only want to send or receive a payment and use bitcoin. They don’t really want to get into all the complexity,” he added.

“Ark starts by assuming that not everyone is a peer, so there will be a liquidity provider on one side and a user on the other side. We acknowledge that this is the natural course of things — even though we may not like it.”

Argentieri, a pragmatist, acknowledges that while the centralized design of Ark might not be philosophically flawless, it is effective.

“The goal again was to have a protocol that starts working backwards from the user perspective and not from an ideal scenario,” explained Argentieri.

“If you think from the user perspective, they really just want to have a user experience that looks like Bitcoin on-chain. With Bitcoin on-chain, you just have a key pair. You just create a simple key and, boom, you can receive,” he added, detailing how Ark works.

A Bitcoin Interest Rate

UTXO owners can serve as liquidity providers for Ark, which Argentieri sees as an opportunity, especially for those in the West.

“In the Western world, we know people really are attached to this concept of yield,” said Argentieri.

“Westerners cannot just hold sats in cold storage and be good with it. They really feel that they’re missing something,” he added with a laugh.

To both obtain liquidity for Ark servers as well as to quench Westerners’ thirst for yield, those willing can become liquidity providers to Ark in exchange for a small fee.

“Ark is really like a way to introduce a bitcoin interest rate,” posited Argentieri. “Ark can be a discovery mechanism for a real true native interest rate for Bitcoin.”

Argentieri described how liquidity providers can share a small percentage of their bitcoin holdings via what he terms a “warm wallet,” a wallet that enables users to hold the keys but that Ark still has access to.

The yield would come in the form of transaction fees via the VTXO model. While Argentieri said that some may look at this as “financializing bitcoin,” he simply sees it as a win-win, a way to help scale while providing a small reward to those who provide the liquidity to help do so.

Scaling Horizontally

While a layer 2 solution like Lightning helps Bitcoin scale vertically, Ark helps Bitcoin scale horizontally, according to Argentieri.

“With Lightning, we set up one address and then two people can do an infinite amount of transactions between each other — but that doesn’t scale,” he said.

With Ark, a UTXO can provide liquidity for an exponential number of transactions compared to the amount of funds in the UTXO. Argentieri gave the example that 100 BTC can provide liquidity for tens of thousands of virtual transactions.

Not only does Ark enable more transactions, but it’s also usable in many of the ways that Bitcoin itself is usable.

“People are very focused on Ark for payments, but the beauty of Ark is that you retain most of the UTXO capability, which means that you can do 95% of things you can do in Bitcoin right now on ARK,” said Argentieri. “You can do multisig and you can open multiple channels with a single address.”

Argentieri also shared that using Ark is nearly as trustless as using Bitcoin, because even if Ark shuts its servers down, you can still get your sats back on-chain.

“If for any reason the server goes away, censors me or goes offline, the whole virtual transactions tree goes on-chain,” explained Argentieri. “This is what we call unilateral exit.”

The Future of Ark

Argentieri said that Ark is hard at work in preparing to bring Ark Node to market, a B2B enterprise-grade offering that Argentieri described as a “plugin for your LND node” that will help businesses with rebalancing liquidity.

At Bitcoin Amsterdam last month, Ark Labs announced a partnership with Boltz to enable off-chain Lightning liquidity management, with the intention of making swaps faster, cheaper and easier via the Ark Node.

Other than that, it seems Argentieri and the team at Ark Labs have a seemingly countless number of new advancements in the works, though, it will take the company some time to roll these out.

“I’m living inside the action, so I wish to release things every week, but engineering takes time, especially when you are the first one doing these things,” he said.

The plan for now is to remain on mission — the latest state of the mission he embarked on ten years ago.

“We can really have a tangible result within the Bitcoin ecosystem,” concluded Argentieri. “People will see Bitcoin payments get better, and we hope to be part of the reason why that will happen.”

David Marcus is taking his experience as the former head of PayPal and Meta Messenger and applying it to building on Bitcoin’s Lightning Network.

At Lightspark’s first partner summit, Lightspark Sync, he and his team rolled out new capabilities for the Universal Money Address (UMA) standard it launched one year ago. These new features will make it easier to tip, pay for subscriptions and invoice over Lightning (and in conjunction with banks in some cases).

At the summit, Lightspark also unveiled a new Bitcoin L2 it has built — Spark — which is interoperable with Lightning and which enables users to use bitcoin (and stablecoins) non-custodially.

I sat down with Marcus the day before Lightspark Sync to learn more about what drives him. We also discussed his strategy in harnessing the power of Bitcoin as a neutral global settlement layer, while still meeting everyday users where they’re at regarding what type of money they like to use.

A transcript of our conversation, edited for length and clarity, follows below.

Frank Corva: I recently saw you post on Twitter that you were happy to be sick on a weekend versus on a weekday because you’re so excited about what you’re working on here at Lightspark. What about this work makes you so excited?

David Marcus: Well, the general idea of changing the way money moves around the world is something that I’ve been obsessed with for a very long time. The fact that we can really change this for potentially billions of people in a profound way is a once in a generation opportunity that I get to actually work on with an amazing team. It’s exciting when you start making progress and when you start to see product market fit.

Corva: Some members of the Lightspark team just showed me the new capabilities of the Universal Money Addresses (UMA) as well as Lightspark’s new Bitcoin L2, Spark. You’re catering to both everyday people who want to move money globally and Bitcoin enthusiasts who care about self-custody. Is the strategy to just get as many people using your products as possible?

Marcus: Just to backtrack a little bit — I don’t need to convince you, but once you get the conviction that Bitcoin is the only thing that can actually be the internet of money because it’s the only asset and network that’s neutral enough to be that, then you have to wonder: Why hasn’t it already won?

If you go back and peel the onion, you start to see, first of all, bitcoin wasn’t moving all that quickly or cheaply. That’s where the Lightning Network came in. The problem with the Lightning Network, while it’s been around for a while, was that it was really hard to implement, really hard to operate and really hard to maintain. And it wasn’t super reliable for transactions.

So, we invested a good chunk of the two plus years of our existence into really making an enterprise grade entry point into Lightning for institutional players, banks and exchanges. That really changed the game, because a lot of them were looking at the lack of activity on the Lightning Network and at the complexity of getting on the Lightning Network and then it became a self-fulfilling prophecy: there’s no activity, it’s too hard, I’m not going to do it

Corva: I’ve heard those complaints before.

Marcus: We broke that cycle by launching Lightspark Connect. That was the foundation, because if you can’t make what I call TCP/IP packets for money — fragments of bitcoin on Lightning — work really well, then you can’t do anything. That was priority number one.

Then we realized we need to enable people to move the currencies they use for their everyday goods and services on the network. That’s when we launched UMA, which is this Universal Money Address standard built on top of LNURL, and extended it so that regulated entities can not only be compliant but can also change in and out of bitcoin and get a quote from the counterparty they’re sending to for the desired currency of the recipient.

That was starting to really work, but then we realized, “Okay, we need to reach [people on] the network that are going to implement UMA natively across the world, but network effects are going to take forever.” That’s where Extend comes in. It makes Bitcoin, Lightning, and UMA compatible with the legacy payment and banking rails, which is really critical.

That’s now launching, and we’re seeing really promising traction with making the entire banking sector basically compatible with Lightning. People have the ability to send and receive money in real time 24/7, no bank holidays, no weekends, nothing.

Then we realized that institutions are building on top of UMA and are offering the ability for their customers — whether they’re consumers or businesses — to claim an UMA address, which is good for peer-to-peer payments, but there’s so much more that we can do. That’s where UMA Request and UMA Auth come in.

Corva: From what I’ve learned thus far, these seem like they will be quite important for merchants.

Marcus: With UMA Request, whether you’re a business or an e-commerce site, you can request money from a wallet [that holds] another currency, and have the transaction settled on Lightning. Then there’s UMA Auth, which is OAuth for money. It’s basically the ability for wallet holders or account holders that are UMA-enabled to delegate push and pull of funds with user set limits. If you make the credit card comparison, you can give your credit card for a subscription, but you don’t set the limit.

So now, if you look at where we are: We basically made Lightning the thing that moves bitcoin fast and cheap — really easy to integrate, maintain, and operate. We figured out a way to move fiat currencies on top of the network in a seamless way. We extended the network to make it compatible with the old banking rails. But what’s missing for Bitcoin now to win fully and entirely and become the true open standard for moving money on the internet? I think there are two things that are holding it back.

One is self custody wallet support. If the network is a closed network and only works between custodial entities, we don’t want that. We want this thing to be as open as possible. Also, for developers, if you need to ask someone for permission to develop something, to test something, to build something, then it’s not like the internet — it’s like CompuServe or AOL.

Support for fast and cheap self-custody wallets on Bitcoin is something that we tried to figure out with Lightning, and it’s basically impossible. I mean, it’s possible but economically non-viable to park that amount of liquidity in front of every self-custody wallet for an eventual future transaction. Then, there are a bunch of different things that we explored with LSPs. They are either non-compliant or have a lot of other issues around how they move money.

The second thing was stablecoins, which are basically a version of a US-dollar denominated bank account for people who can’t have the real thing. As they grow in popularity and usage, if we can’t make them travel natively on Bitcoin, then we’re at a disadvantage. And so that’s why we built Spark, which is what we see as a totally non-linear jump forward for Bitcoin that will enable self-custody wallets to interoperate fully with Lightning.

It really extends the reach of self-custody to Lightning. It makes stablecoins a reality on Bitcoin, which they couldn’t be as well on Lightning, because, if you look at Taproot Assets and [other protocols like it], they’re pretty good on top of Lightning, but then you go back to the problem of pairwise channels for each of those stablecoins. In a world where you’re going to have thousands of stablecoins, it’s just not going to work.

We believe Spark solves the last two problems standing in a way of Bitcoin becoming the internet of money.

Corva: UMA Auth enables people to make payments within other apps. Was it challenging to build something that accomplishes this, something that makes payments and tipping not only possible but easy?

Marcus: There are several things here to unpack. First of all, making Lightning work really well for regulated entities was really hard. Once you’ve done that, you need to build something that enables them to move the money that people want to use and do it in a way in which regulated entities can meet their compliance requirements. That’s something that’s non-trivial.

Then, the Extend piece is actually understanding how payment systems work and really doing the work — which is a lot of work — to make the network compatible with existing payment rails.

So, A, it’s a lot of work. B, it’s a lot of understanding of not just how Bitcoin and Lightning work, but also how traditional payments globally work, what the regulatory landscape looks like, and what people, what companies and regulated institutions actually need to trust the network that they’re going to connect to and offer to their customers.

Corva: Do banks see the benefits in using Lightning as a settlement layer? In some ways, it seems like with what you’ve built, there would be no need for CBDCs, which would help keep smaller banks in business, because it isn’t a given that CBDCs will be able to be used for international remittances.

Marcus: Some banks do, and some others will eventually, but they’ll take a little more time.

At the end of the day, if you build a more efficient network that enables global money movement faster, cheaper, in real time 24/7 and with no blackout dates, then that’s where money is going to flow and the financial system and the ecosystem players are just going to need to adapt to that.

If you’re a bank you’re going to be able to offer global payments to your clients at a cheaper rate and have a margin on top of that, which you know is going to be very comfortable if you’re competing with the current alternatives — international wire transfers are still forty five to fifty dollars.

Corva: You’re working with Nostr Wallet Connect (NWC) and the team from Alby. It seems like you really have your ear to the ground regarding new technologies coming to market in the Bitcoin, Lightning and Nostr spaces.

Marcus: Absolutely. With Nostr Wallet Connect, there’s actually a really good solution to the problem of delegating Auth, or delegating the ability to push and pull from a wallet with a protocol, that is starting to have nascent network effects in the Bitcoin and Nostr communities.

It’s really good work, and so why not extend it and enable more things to happen with Nostr Wallet Connect for mainstream use cases? That’s the way we look at things. We look at what the entire community is building, we contribute to those efforts, and then we try to extend it to bring it to mainstream consumers so they can use it in a way that is going to be familiar and not foreign to them.

Corva: Do you have any final thoughts you’d like to share?

Marcus: We’re really excited. We feel like all of these capabilities that we’ve been hard at work on in are almost two and a half years of existence are reaching a tipping point right now where basically there are all of the capabilities that are required for Bitcoin to decisively win at becoming the open internet for money, and now it’s just a matter of executing, of finding all of the entities that are going to not only share that vision but execute it with us.

That’s why — to your point about me not wanting to be sick on a work day — I feel like this is just too exciting to not work on every day.

At Lightspark Sync, Lightspark’s first partner summit on Thursday, the company announced new products and features that will allow users to make global payments with both bitcoin and fiat.

The company announced that it has launched an alpha version of Spark, a Bitcoin Layer 2 that’s interoperable with Lightning and that makes it cheaper to onboard users to a non-custodial Bitcoin layer.

The company also announced new capabilities for UMA, the company’s open-source and regulatory compliant payment solution that makes sending money as simple as sending an email.

With UMA Extend, the Lightning Network can serve as a bridge between traditional banks globally, while with UMA Auth and UMA Request, UMA users can tip, pay subscription fees and make payments to merchants within apps.

Spark — Lightspark’s Bitcoin Layer 2

Spark is a Layer 2 protocol for Bitcoin that leverages statechain technology. In short, users can hold fractions of bitcoin off-chain, and transfer these by sending private keys to other users (rather than signing transactions with the keys).

Lightspark created Spark to better support the onboarding of users to the Lightning Network, which normally requires an on-chain transaction for each payment channel as well as the locking up of some amount of bitcoin in these channels so users can send and receive transactions.

The layer 2 was primarily borne from the frustration that the Lightspark team encountered in trying to create a non-custodial Lightning wallet for users.

“Self-custodial Lightning wallets, especially at scale, just aren’t viable,” Lightspark CTO Kevin Hurley told Bitcoin Magazine.

“If you are opening channels for billions of users, fees are going to go through the roof, and you’re going to fill up block space. It’s just something that’s not going to be reasonable and you lock up liquidity for every single user,” he added.

Hurley also shared that Lightspark didn’t want to wait for the enabling of Bitcoin opcodes (like CheckTemplateVerify or TapleafUpdateVerify) that would make it cheaper to open new Lightning channels. Lightspark wanted to offer users a non-custodial option immediately.

So, they built Spark, a Bitcoin Layer 2 that offers users cheap, instant payments as well as a permissionless, unilateral exit to the Bitcoin base layer. It also enables offline receive, or the ability to receive bitcoin even when your device isn’t connected to the internet.

Besides statechains, Spark also utilizes atomic swap technology. Its design is similar to that of Mercury Layer in that it enables the off-chain transfer of ownership of Bitcoin UTXOs while benefiting from near instant and fee-free transactions, according to Hurley.

“Mercury has a lot of core limitations that we go beyond,” explained Hurley.

“In Mercury, for example, you can transfer whole UTXOs only. You have absolute time bombs where you have to go back on chain at some absolute time. So, you can only do so many transactions. Also, we pull in different pieces like connector transactions from Ark, for example, but, other than that, we’re not similar to Ark at all,” he explained.

“I think it’s hard to compare it to something, because it pulls in a lot of different components, and I think the trade-offs that we chose to make are different than many others probably chose to make.”

Besides bitcoin, it’s also possible to issue and use stablecoins on Spark. Or you can issue stablecoins via Taproot assets, LRC-20 or RGB on the base layer and transfer them to Spark.

A unique dimension of Spark, though, is that the assets on the layer 2 are all UMA enabled.

“You can now have non-custodial users sending directly to the bank accounts of UMA Extend users,” said Hurley, mentioning one of the new functionalities of UMA addresses.

UMA Extend

UMA Extend integrates the Lightning Network with traditional banking systems, allowing users to make international bank transfers in seconds. With this new technology, UMA Extend users can send any other UMA Extend user a near instant cross-border payment from one bank to another over Lightning as easily as sending an email.

“It’s designed to facilitate money movement across any currency,” Nicolas Cabrera, VP of Product at Lightspark, told Bitcoin Magazine. “I can be in Brazil sending my local currency, the Brazilian real, to a user based in Europe that wants to receive euros or someone in the US who wants to receive USD.”

The Brazilian reals leave the sender’s bank account, are converted into sats by the bank (or an entity like Zero Hash, if the banks can’t touch crypto), which are then received by the recipient’s bank, which converts it back into euros, USD of whatever currency the recipient holds in their bank account. All of this occurs within 30 seconds or so, a radical shift compared to the two to three days it often takes for international money transfers to settle.

“This is the first time connecting the Lightning Network to traditional banking routes and bank systems,” Cabrera added.

UMA Extend utilizes Real-Time Payments (RTP), which enables real-time payments for federally insured depository institutions in the United States, and comparable services in the other countries in which UMA Extend is available. All banks in the US who use RTP support Extend. Currently, Lightspark’s partners support on- and off-ramps for 44 fiat currencies in over 100 countries.

The traditional financial institutions involved with these transactions will set the fees for the transactions, which tend to range between 0.25% and 0.5% — significantly cheaper than the 6.35% customers often pay to make international remittance payments via traditional financial rails.

Those interested in using UMA Extend can do so via this link.

UMA Auth

At the event, Lightspark also introduced UMA Auth. The technology leverages OAuth (Open Authentication) technology (the backend tech for when a website gives you the option to sign into a third-party app or website with Google or Facebook), an open-standard authorization protocol that provides users with secure access to a website or application.

UMA Auth was built using Nostr Wallet Connect (NWC), a protocol developed by the team at Alby. NWC now supports UMA features like cross-currency transactions and client app registration.

“We wanted to expand the coverage of UMA beyond wallets to applications,” Shreya Vissamsetti, a member of the Lightspark engineering team that works on UMA, told Bitcoin Magazine.

“UMA Auth is a new extension on top of UMA that allows you to integrate payments directly into an application. The idea is that it’s a lot like OAuth, but for money,” she added.

“All you have to do is input your UMA address and then we form a connection to your Lightspark wallet straight from the application. That gives the app access to communicate with your wallet and push money in right from the application.”

UMA Auth enables users to do everything from tipping their favorite artists to paying a subscription fee to paying a friend through their preferred messaging app.

“Say I’m listening to Taylor Swift,” began Vissamsetti.

“I can link my UMA account, and if my favorite song is playing, I can just tap a button and send her a super small tip,” she explained.

“Tipping is one of the main uses we’re going after with this product,” said Cabrera. “Lightning is again a good foundation layer for us because it allows for sending small amounts.”

UMA Request

UMA Request is another new dimension of UMA, one that allows any UMA user to request a payment from another UMA user.

Merchants can use UMA Request to request payments via an invoice, which comes in the form of a QR code, for the product sold or service rendered. UMA Request also supports zero-sum invoices, through which invoice recipients can pay whatever amount they’d like.

“Previously with UMA, the sender initiated the payment, but we’ve flipped it around,” said Vissamsetti.

Another standout feature of UMA Request is that it ensures both parties involved in the transaction receive a record of the transaction.

UMA Request makes purchasing items online — especially across borders — easier and cheaper than using credit cards.

Moving Forward

Lightspark’s CEO David Marcus, the former president of PayPal, believes that it’s only a matter of time until more banks and platforms come to adapt new technologies like UMA Extend, UMA Auth and UMA Request.

“At the end of the day, if you build a more efficient network that enables global money movements to move faster, cheaper, in real time 24/7 with no blackout dates, then that’s where money is going to flow and the financial system and the ecosystem players are just going to need to adapt to that,” Marcus told Bitcoin Magazine.

Regarding Spark, the Lightspark team is looking for feedback from users on how to improve the product.

“We are going to fully engage with the community,” said Hurley.

“We want to make this completely out in the open, completely open-source. Anyone can audit it, spin up their own versions if they want to,” he added.

“We want this to be a collaborative thing where the community joins in, where they hopefully submit pull requests and help find things that they want to improve.”

Christina Smedley, co-founder and Chief Marketing and Comms Officer at Lightspark, echoed Hurley’s sentiment as she discussed both Spark and UMA’s new functionalities.

“We’re trying to [onboard] the next billion or couple of billion,” Smedley told Bitcoin Magazine, “so it’s really important that what we do is open-source and community-led.”