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Second, a Bitcoin development lab, has just launched Bark on the mainnet. This is not a beta or a testnet—it’s the real network. The idea is to enable Bitcoin payments with self-custody without forcing users to struggle with Lightning channels or pay exorbitant on-chain fees.
What Bark Changes for Bitcoin Payments
Bark is Second’s in-house implementation of the Ark protocol. Ark is a layer 2 solution that allows a large number of users to share on-chain UTXOs through pre-signed off-chain transaction trees. Essentially, the fees are distributed among several people, but each retains control of their funds. That’s the key point. No channel manager, no pre-allocation of liquidity. These are two issues that have long pushed people towards custodial solutions—and thus towards losing control of their Bitcoin. Ark aims to solve this neatly. The Lightning Network remains a benchmark, but its technical complexity has always hindered adoption among non-tech users. Bark takes the opposite approach: making self-custody as simple as a standard bank transfer.
Second’s Ark server is now open to the public for payments.
The Bark SDK and Apps Available at Launch
Second delivers an entire ecosystem, not just a bare protocol. The Bark SDK is written in Rust, with bindings for Kotlin, Swift, React Native, Flutter, Go, Python, and WebAssembly. Seven environments covered from day one. For servers, there’s also Barkd—a standalone wallet daemon with a REST interface and an OpenAPI spec.
Four applications are already mainnet-compatible at launch. Noah, a complete Ark mobile wallet, combines a React Native frontend with a Rust backend. Arke is native iOS, design-focused, built on the open-source UX principles of bitcoin.design. Satsigner brings Sparrow-style UTXO management and multisig workflows to mobile users—like the tool power users have been waiting for. And Bark Wallet, an Umbrel app, manages Ark, Lightning, and on-chain payments in a single interface.
For merchants, Second has also released a BTCPay Server plugin. This allows for self-custody Lightning payments without opening a channel or touching liquidity. Quite a boon for merchants who want to accept Bitcoin without delegating custody to a third party.
The breadth of the SDK—seven languages, a server daemon, four apps at launch—clearly bets on developer adoption. Second isn’t banking on a single flagship wallet. The team prefers to build a broad technical base and let third-party developers take it from there.
$5.1 Million Raised, Eleven People, Former Blockstream Engineers
Second has raised $5.1 million from a private investor. The team consists of eleven people, including several former Blockstream engineers. Not a huge staff for such an ambitious project, but probably sufficient to keep pace with a still-young protocol.
The competitive landscape is crowded. Ark Labs is pushing Arkade, its own version of the protocol. Solutions based on statechains also exist. Everyone is chasing the same Holy Grail: self-custody + decent UX. Second is not alone in the race, far from it.
What sets Bark apart from other attempts is perhaps precisely the SDK-first approach. Many layer 2 protocols have launched a single wallet and hoped that would suffice. Second is betting on developer tools, hoping the ecosystem will grow around them. It seems more solid in the long term, but nothing is guaranteed. Real adoption will take time.
Second will host a live AMA session on Stacker News on June 9 at 10:00 AM EST.
The team of eleven people, backed by $5.1 million, has decided to release everything at once: protocol, multi-language SDK, server daemon, four apps, BTCPay plugin. A lot of ground to cover for a small structure.
Hub: Bitcoin: Price, News, and Analysis
Frequently Asked Questions
What is Bark and how does it differ from the Lightning Network?
Bark is Second’s implementation of the Ark protocol, launched on the Bitcoin mainnet. Unlike the Lightning Network, Bark does not require channel management or pre-allocation of liquidity, simplifying self-custody payments for ordinary users.
How much has Second raised and what is the size of the team?
Second has raised $5.1 million from a private investor and operates with a team of eleven people, including former Blockstream engineers.
What applications are available at the launch of Bark on the mainnet?
Four apps are compatible at launch: Noah (a complete Ark mobile wallet), Arke (iOS native design-focused), Satsigner (mobile UTXO and multisig management), and Bark Wallet (an Umbrel app supporting Ark, Lightning, and on-chain).
