Development lab Second has brought Bark into production, its implementation of the Ark protocol, aiming to make self-custody accessible to everyone.
Second, a Bitcoin development lab, officially launched Bark on the Bitcoin mainnet on June 9, 2026. Bark is Second’s implementation of the Ark protocol and aims to make self-custody bitcoin payments accessible to both developers and everyday users, eliminating the complexity typically associated with the Lightning Network or on-chain transactions.
Bark is built on the Ark protocol, a second-layer solution that allows a large number of users to share on-chain UTXOs through pre-signed off-chain transaction trees, distributing fee costs among participants while preserving individual self-custody. Unlike Lightning, Ark requires no channel management or liquidity pre-allocation, eliminating the critical pain points that have long pushed mainstream users toward custodial alternatives.
CEO Steven Roose explained the project’s philosophy in a post: “We wanted to make it incredibly simple for users to get started with self-custody bitcoin, hold it and spend it, without surprise fees and without having to manage channels or liquidity”. Second’s Ark server is now publicly accessible for payments.
The launch includes a complete developer toolkit – the Bark SDK – written in Rust with bindings for Kotlin, Swift, React Native, Flutter, Go, Python and WebAssembly. For server environments, Second also ships Barkd, a standalone wallet daemon that exposes a REST interface with OpenAPI specifications. Several applications are already enabled on mainnet at launch: Noah is a full-stack mobile wallet pairing a React Native frontend with a Rust backend; Arke is a design-oriented native iOS wallet built on open-source UX principles from bitcoin.design; Satsigner brings Sparrow-style UTXO management and multisig flows to mobile; Bark Wallet is an Umbrel app supporting Ark, Lightning and on-chain payments. A BTCPay Server plugin, also developed by Second, allows merchants to process Lightning payments in self-custody without opening channels or managing liquidity.
Second has raised $5.1 million from a private investor and operates with a team of 11 people. The company has attracted notable talent in the sector, including former Blockstream engineers. The launch comes at a time of fierce competition in the Bitcoin layer-2 space, with multiple protocols – including Ark Labs’ Arkade and statechain-based solutions – competing to bridge the gap between self-custody and user experience.
