Ark Protocol Goes Live on Bitcoin Mainnet With Two Implementations

Ark protocol, a Bitcoin-based payment architecture designed to sidestep Lightning Network's liquidity constraints, now has two implementations live on mainnet. Bitfinex, which covered Ark as an unimplemented proposal in 2023, reported this week that Arkade from Ark Labs and Bark from Second are operational with commercial integrations.

The system uses virtual transaction outputs, or VTXOs. These are pre-signed, off-chain Bitcoin outputs backed by funds in a single on-chain transaction. Each VTXO has a unilateral exit path, letting the holder recover bitcoin if the provider stops cooperating. Bitfinex described the setup as giving users outputs with built-in exit guarantees, not a balance controlled by a third party.

Bark and Arkade share the same VTXO architecture. Bark focuses on self-custodial bitcoin payments and Lightning interoperability. Arkade extends the model toward a broader execution environment with support for stablecoins and swaps. In October 2025, Ark Labs launched Arkade Assets, extending VTXOs to handle fungible assets.

Integrations followed. Lendasat, now Satora, launched Lendaswap in November 2025, using Arkade for swaps between bitcoin and stablecoins on other chains. Hodl Hodl added Arkade to its escrow system in May 2026 to speed trade settlement. Bitrefill made Arkade a payment option on its gift card platform the next month, offering instant fee-free purchases.