A new upgrade, ArbOS 40 "Callisto," unlocks powerful new primitives for account abstraction, zk tooling and developer UX.

The ArbOS 40 “Callisto” upgrade integrates Ethereum’s Pectra features into Arbitrum and is now active on both Arbitrum One and Nova, introducing advanced primitives for account abstraction, zero-knowledge tooling, and enhanced developer experience across Ethereum’s largest Layer-2 ecosystem