Introducing the OP Stack

The Optimism Collective is an attempt to birth a new form of organization, built on the belief that that humans > capital and impact = profit, and committed to tackling the coordination problems which crypto as a whole has yet to solve.

Ultimately, Optimism isn’t building a blockchain—it’s building a digital society.

But ambitious goals demand equally ambitious infrastructure.

Today, we’re proud to introduce the next evolution of Optimism’s scalability architecture: the OP Stack.

The OP Stack is a modular, open-source blueprint for highly scalable, highly interoperable blockchains of all kinds. Not just rollup. Not just optimistic.

The OP Stack is a bet on the ingenuity of the entire Ethereum community. It makes it easier than ever to build your own blockchain, empowering you to focus on what matters–the cutting edge.

The OP Stack is also a bet that the future is neither multi-chain nor mono-chain. Instead, we believe that a group of highly integrated chains will form an emergent structure, the Superchain, which powers the collective.

This blog post builds upon talks given by OP Labs’ Karl Floersch and Kelvin Fichter at Devcon 6.

The Past

As OP Mainnet approaches 2 years in production, it’s pretty humbling to look back to our beginnings as starry-eyed scalability researchers all those years ago. Over that long and winding road, two themes have remained constant: minimization and modularization.

One formative early lesson on this path was when a wise wandering sailor named geohot replaced a 6,000-line transpiler we had worked on for months with a 300-line modification to the Solidity compiler that took just a handful of days. Geohot forever raised our bar for the simplicity and elegance required to become an open source standard across the entire Ethereum ecosystem.

We took this lesson to heart. In 2021, we made the difficult decision to throw away our original rollup design, the OVM, in favor of a more modular approach which separated execution from proving. And boy, did it pay off–the result, our EVM Equivalence upgrade, still holds its own against the latest releases from alternative rollups, despite being nearly a year old.

The Present

For the past year, we’ve been heads down working towards our next release–Bedrock–which doubles down on those principles of modularity and minimization. This new design leverages some modularity introduced for The Merge–consensus/execution layer separation–to make Optimism’s code stupid simple. With 100x less code than our original OVM, and only 1,000 lines of code required to implement an alternate client (looking at you, Optimistic Erigon 👀), we knew we had something truly powerful on our hands.

And as this new, highly modular codebase started to reach stability… something strange began to happen. People started forking the codebase and using it for things we’d never even imagined.

OP Mainnet was already the most forked ORU out there, but these new forks were weird. We were used to forks adding small features or swapping out the data availability layer to decrease fees. We did not expect the next fork to be anything like what we got: OPCraft.

Lattice, the fantastic team behind this project, took the Bedrock codebase and put an entire voxel game on-chain. The OPCraft world lives on-chain, mining in-game blocks produce on-chain transactions… crazy stuff.

After OPCraft came yet another ridiculous fork, this time from the crew over at 0xPARC — the Optimistic Game Boy. Nalin Bhardwaj and Adhyyan Sekhsaria swapped out Bedrock’s execution engine with a Game Boy emulator, effectively building a Game Boy Rollup. Even better, since the Game Boy emulator could compile down to MIPS, the entire execution of the emulator was fault provable via cannon. Wow.

It was in this moment that we realized: geohot’s sage advice—and our multi-year bet on elegant, standardized, open source software—was beginning to bear fruit. We knew we had something special on our hands. We had started by reusing Ethereum to modularize our own codebase, and now the Ethereum community was reusing our modules to build things that had never been seen before.

So… what were we supposed to do?

The OP Stack

The OP Stack is the code powering Optimism’s next-gen architecture. It’s a series of modules that work together to form coherent, reliable blockchains. Each of these components implements a specific layer of the stack. Here’s what these core components look like:

Modules of the OP Stack, with the Bedrock release configuration in white.
Modules of the OP Stack, with the Bedrock release configuration in white.

Each layer of the OP Stack is described by a well-defined API, to be filled by a module for that layer. You can easily modify existing modules or create your own entirely new modules to fill the needs of whatever application you’re building. Want to swap out Ethereum for Celestia as a data availability layer? Sure! Want to run Bitcoin as the execution layer? Why not!

The OP Stack is the first realization of the modular blockchain theory. We’re finally moving beyond charts that describe how this might work to a concrete codebase where you actually get to fit these components together. If you’re a developer, you can find much more information about the API for each component and how the different components work in tandem to create a modular chain system in Kelvin’s Devcon talk.

The OP Stack is being built, first and foremost, for the Optimism Collective. It’s Optimism’s way to future-proof the entire ecosystem. Perhaps the most important way the OP Stack achieves this is the abstraction of the proof layer when settling funds onto another chain. As long as the proof layer satisfies the proof API, it can be slotted into the system. All of this can happen with zero impact on user experience. Long-term, this makes it possible for OP Chains to adapt to newer proof systems as well.

The Far Future

Bitcoin rollup? Bitcoin Rollup! Gameboy Plasma? Gameboy plasma! Tamagotchi Bitcoin Rollup? …Tamagotchi Bitcoin rollup!

Releasing the OP Stack will the first step in an explosion of highly compatible L2s and L3s. We lovingly call these op-chains. By sharing and contributing back to a hardened, standardized, and modular codebase, all of these systems can work together to build the future of Ethereum. With a shared message-passing format, these chains can easily communicate with each other without custom adapters for each and every chain.

The OP Stack is an opportunity to create something amazing. We have the opportunity to scale Optimism’s values across a networked collective of blockchains—and core to that vision is Sequencing. Although many chains will want to run their own Sequencers, the reality is that Sequencing can be hard to set up and, in the long-term, will need to be decentralized to provide the liveness guarantees that users expect. It’s likely that many more chains won’t want to run their own Sequencers, just like Optimism decided to piggy-back on Ethereum’s consensus layer to avoid needing its own validator set.

When multiple op-chains share a Sequencer Set, they get access to a fantastic feature: atomic cross-chain composability. Sequencers that produce blocks on multiple chains at the same time can guarantee atomic interactions between those chains. This works because a single entity has the ability to produce blocks on each chain — they don’t need to rely on other validators to include these atomic transactions. Op-chains that opt in to the Optimism Collective’s shared Sequencer Set become part of a system where the boundaries between chains dissolve.

Even though it’s made of multiple chains, the addition of atomic cross-chain interactions means that this feels to end users like a single logical chain. We’re calling this emergent endgame the Superchain.

As with everything we do, the Superchain exists to continue to push ourselves and the Ethereum ecosystem towards the vision of a sustainable and independent digital society. By opening up the Collective’s resources to not just OP Mainnet, but also to the many different op-chains that plug into the Superchain, it becomes possible for entirely new chain ecosystems to collaborate towards this future.

The Near Future

The OP Stack is still in the early stages of being turned into a standalone product. Our primary objective for the next few months is still to ship the Bedrock upgrade, the flagship OP Stack release, to OP Mainnet. Eventually, the Bedrock codebase will be refined into an OP Stack release, with things separate documentation for how you can run and modify your own OP Stack-based op-chain.

For now, if you’re interested in playing with the OP Stack, get in touch — or, if you’re feeling as adventurous as our early adopters, Optimism’s code is always developed in the open! 😉

Together, we will create the future of coordinated, collaborative cyberspace.

Together, we will summon Ether’s Phoenix.

The future isn’t multi-chain or mono-chain, it’s Superchain.

Stay Optimistic, nerds.

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