Bitcoin development lab Second launched Bark, its implementation of the Ark protocol, on Bitcoin mainnet this week. The layer-2 solution offers self-custodial bitcoin payments without requiring users to manage Lightning channels or deal with on-chain transaction delays. Bark is live with a publicly accessible Ark server and multiple supporting wallet applications.
How Bark works
Bark uses the Ark protocol, a layer-2 system that relies on pre-signed, off-chain transactions arranged in UTXO trees. That structure lets multiple users share fee costs while keeping control of their own coins. Unlike Lightning, there are no channels to open or close, and no need to pre-allocate liquidity — two common UX pain points that have kept self-custodial payments niche. CEO Steven Roose said the goal is to make self-custodial bitcoin easy, without surprise fees or the hassle of managing channels and liquidity.
Multiple apps go live
Alongside the Bark server, Second released several mainnet-enabled applications. Noah is a mobile wallet built with React Native and Rust. Arke is a native iOS wallet. Satsigner handles UTXO management and multisig. Bark Wallet runs as an Umbrel app and supports Ark, Lightning, and on-chain transactions. There's also a BTCPay Server plugin. The Bark SDK itself is written in Rust with language bindings for Kotlin, Swift, React Native, Flutter, Go, Python, and WebAssembly. A standalone wallet daemon called Barkd comes with a REST interface and an OpenAPI spec.
Team and backing
Second has raised $5.1 million from a single private investor. The team of 11 includes former Blockstream engineers. That background shows in the protocol design — Ark's architecture borrows ideas from Blockstream's research on sidechains and off-chain transactions.
Competition and the next step
Bark lands in a crowded Bitcoin layer-2 field. Ark Labs has its own implementation called Arkade, and statechain-based solutions are also competing for the same user base. Second isn't stopping at the launch: the company will host a live AMA on Stacker News today, June 9, at 10:00 AM EST. Anyone curious about how Bark works or what's coming next can ask questions directly.
