Arbitrum Rollup is live on testnet

The first and only working Rollup system for general smart contracts has launched. Port your Solidity contracts today.

Steven Goldfeder
Feb 11 · 3 min read

We here at Offchain Labs are thrilled to announce that Arbitrum Rollup is live on testnet. If you’re looking to massively scale smart contracts on Ethereum without compromising security, Arbitrum Rollup is right for you.

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Try Arbitrum Rollup today

What’s Rollup?

Great question! So good, in fact, that we have a whole post dedicated to explaining Rollup and comparing its various flavors.

Rollup is a general approach to scaling open contracts, that is, contracts that everyone can see and interact with. In rollup, calls to the contract and their arguments are written on-chain as calldata, but the actual computation and storage of the contract are done off-chain. Somebody posts on-chain an assertion about what the contract will do — a list of actions taken by the contract, such as payments made, and a cryptographic hash of its state after the contract has executed the calls that have already been posted on-chain. We can think of the assertion as “rolling up” all of the calls and their results into a single on-chain transaction.

Since contract execution and storage are moved off-chain, on-chain gas costs are drastically reduced.

What’s Arbitrum Rollup?

Arbitrum Rollup is a Rollup system running on top of Ethereum that’s optimized for general smart contracts with high security, high throughput, and strong censorship resistance. If you’re interested in the nuts and bolts of how it works, check out our detailed post.

Unlike some other rollup systems, Arbitrum rollup doesn’t limit the types of contracts you can write or require you to re-write your applications using unfamiliar abstractions or languages. Arbitrum has full smart contract support and ships with a Solidity compiler so that you can easily port existing contracts or begin developing new ones.

But perhaps the biggest differentiator between us and every other Rollup proposal for general smart contracts is that we have open-source code that works on testnet today. If you want to build a scalable smart contract on Ethereum today, with high security and low costs, Arbitrum is the only show in town.

What’s next?

Today’s launch resulted from years of research and engineering, first as academics at Princeton University and continuing at Offchain Labs. But we’re far from done. Here are some things you can expect from us going forward:

  • More demos. Over the next few weeks, we’ll be showcasing popular demo apps that run seamlessly on Arbitrum, and at a fraction of the cost of running them natively on Ethereum.
  • Partners. We can’t do this alone! Stay tuned for announcements about companies that will be working with us to harness the power of Arbitrum and bring scalable smart contracts to the hands of more developers.
  • To Ethereum mainnet and beyond! We’re already hard at work gearing up for our mainnet launch, so stay tuned for upcoming announcements. And we’re not stopping with Ethereum, either. Arbitrum is coming soon to a blockchain near you.
  • Arbitrum Sidechains and Channels. Rollup is awesome — particularly for “open world” smart contracts which don’t have a fixed set of players. But, it turns out that for a large class of contracts, we can move even more off-chain, achieving greater scalability and even lower costs. We’ve written a lot about Arbitrum Sidechains and Channels, and plan to launch them later this year.

I’ve read enough. I want to start BUIDLing!

We don’t blame you. You can download the open-source code, read the developer docs, and get started. Join our discord where you can hang out with our team, let us know about the awesome things you’re building, and we’ll be happy to answer any questions that come up along the way.

If you’ll be participating at EthDenver, build your project on Arbitrum! We’ve written up a quick start guide for EthDenver, will be around to provide technical support to teams building on Arbitrum, and are offering some great prizes for our favorite hackathon projects.

Offchain Labs

Creating Arbitrum, an Ethereum scaling solution

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