Arbitrum Updates: Buckle Up

Offchain Labs
Offchain Labs
Published in
3 min readMar 25, 2021


Whooo. Deep breath. We’ve been quite busy over the past few months and are excited to share our progress and roadmap with you. It’s been a wild ride, but keep your seatbelts on as we’re moving fassst.

Release Candidate Testnet

We’ve just launched our V4 testnet which is our mainnet release candidate.

Sorry folks gonna need a bit more excitement. Let’s try again. It’s our mainnet release candidate!!

We’ve hosted an open and permissionless testnet for five months now, and it’s been an incredible experience for testing our software in the wild and learning from our users. So thanks to everyone who’s developed on and used Arbitrum to date and provided us with valuable feedback. We’re listening closely.

The new testnet includes simplifications to the rollup protocol, performance upgrades for the node software, and a host of awesome new features like support for BLS signatures (!) to further reduce our L1 gas costs and an upgraded bridge that supports general calls from L1 to L2 and L2 to L1.

What’s Next

We’re just about there.

We’ll be giving the release candidate a bit of mileage on testnet before shipping it off to mainnet. We will also be announcing many of our launch partners, so definitely keep on the lookout for that!

Join our Discord and follow us on Twitter for the latest updates.

What will our mainnet release look like

Just like our testnet, our mainnet will be open and permissionless from day one. We believe that the value of the Ethereum ecosystem comes from having a wide and diverse set of teams and applications building with us, and we won’t be picking winners or playing favorites. While we’re always happy to work with and support teams that are building on Arbitrum, Arbitrum is a community project and you don’t need our permission to launch on it.

For the first few months of mainnet, we’ll be maintaining the ability to upgrade and pause the system to respond to any security events. Despite having done significant security diligence on our code, we believe this is necessary until we have some mainnet mileage behind us. To keep ourselves honest, we’ll call our initial release a mainnet beta and we will continue to use this moniker until we’ve phased out the controls. As we get closer to mainnet, we will be talking about this in much more detail.

Why Arbitrum?

Arbitrum is the most optimistic Optimistic Rollup on the market.

  • Typical transactions on Arbitrum use 2–3k Ethereum gas. With the introduction of BLS signatures in our release candidate, developers can now cut these costs down even further.
  • Arbitrum is EVM compatible on the bytecode level so no need to rewrite your code or use any custom compilers or new tools to download. Your Solidity/Vyper code just works as does whatever tooling your using (e.g. Truffle, Hardhat, Brownie).
  • Arbitrum breaks out of Ethereum’s contract size limit and transaction gas limit. Want to do a large contract deployment on Arbitrum? No problem! Have a transaction that uses more gas than is available in an Ethereum block? Go for it!

Get Ready

How can you best prepare for our upcoming launch?

  • Build on the testnet! Familiarize yourself with Arbitrum and be ready to use mainnet as soon as it’s live.
  • Help us test! Deploy your contracts on our testnet and try using some live dapps.
  • Make sure you are among the first to access our upcoming announcements by joining our Discord and following us on Twitter.



Offchain Labs
Offchain Labs

We’re Building Arbitrum, a scaling solution for Ethereum. Learn more at and