Over 250 teams have requested developer launch access, which can save a lot of gas in the Ethereum blockchain.
Fair Launch
Arbitrum announced itself to a fair launch. It commits to putting projects of all shapes and sizes on the same footing, and nobody gets priority access. To facilitate this, Arbitrum One is initially open to all developers who have requested access. They’ll open it up to end-users once there’s a quorum of live projects deployed on the network and are ready to go live. Arbitrum guarantees that all projects with access granted to them will have at least two weeks to build and test before we open Arbitrum One to everyone.
Why is named Arbitrum One?
They named their mainnet chain, Arbitrum One, and assigned a chainid of 0xa4b1 (decimal: 42161).
Arbitrum is the technology and Arbitrum One is the flagship chain. Currently, their whole teams focus is on Arbitrum. Their partners like Etherscan and Alchemy are supporting the Arbitrum One chain. They differentiated the name of the tech from the name of the chain incase they develop another rollup chain using the Arbitrum technology.
In short, Arbitrum One is a mainnet Ethereum L2 chain built using Arbitrum technology.
FEES
Arbitrum reduces fees by more than 50x for most workloads that we’ve seen, and it is not free like all rollups. They use the majority of their fees to pay for posting calldata on Ethereum. There are also costs to operate the chain and the supporting infrastructure. Arbitrum uses Eth as its Native token, and fees will be paid in ETH on L2. To use the chain, users first have to use the Arbitrum Bridge to transfer ETH from Ethereum to their L2 wallet