What is OP Stack


The OP Stack is a recognized, open-source framework championed by Optimism and is overseen by the Optimism Collective. It acts as a vital tool for both the Ethereum and Optimism communities. Its main role is to bolster Optimism, offering key software tools, which are now integral to the Optimism Mainnet, and soon, the Optimism Superchain and its governance model. The core idea behind the OP Stack is to foster growth and creativity in the Ethereum realm. By presenting a developer-friendly environment, it paves the way for forefront developments, making the task of blockchain creation more straightforward.

The foundational belief of the OP Stack is that the coming era won't be monopolized by either single-chain or multi-chain models. Instead, a unified chain network, known as the Superchain, is predicted to rise, enhancing the combined ecosystem. The OP Stack is made up of several software pieces, delineating various strata of the Optimism environment. These elements can either shape particular layers or act as units within them.

While its primary focus is L2 blockchain infrastructure, the OP Stack holds the promise of expanding to other areas like block search tools, communication systems, governing structures, and beyond. The Optimism Bedrock, the newest version of the OP Stack, facilitates the launch of top-notch Optimistic Rollup blockchains. The interfaces for each tier within the OP Stack are closely tied to this Rollup setup, ensuring smooth linkage and alteration of units to fit distinct operational needs.

A central feature of the OP Stack is its adaptive blockchain approach, which ensures long-term relevance. The stack simplifies the proof layer during transfers to another chain. As long as the proof layer aligns with the proof interface, it can be effortlessly integrated into the framework, ensuring a consistent user interface. This flexibility heralds opportunities for Optimism to embrace emerging proof methodologies down the line.

Core Design Philosophies

The OP Stack is a suite of software tools tailor-made for devising L2 blockchain systems, masterfully assembled by the Optimism Collective to fortify the Optimism infrastructure. When assimilating tools into the OP Stack, three cardinal design tenets stand out: Utility, Simplicity, and Extensibility. Software adhering to these tenets is deemed essential, rendering supreme value to the Optimism Collective.


For a software piece to be integrated into the OP Stack, it must substantively empower the Optimism Collective. This criterion is pivotal in assessing a component's fit for the stack. For instance, a reliable open-source block search tool that aids users in scrutinizing the Superchain would be a worthy addition. While Utility is pivotal, it's equally vital to champion innovation and novel ideas. Embark on pioneering endeavors and conceive groundbreaking projects, even if their direct use isn't evident. The overarching aim is to relish the process and nurture a robust ecosystem under the Optimism Collective's banner.


Inclusion of convoluted code into the OP Stack is shunned in favor of Simplicity. This emphasis lets the Optimism Collective slash technical complexities, enabling a focus on innovation rather than redundant tasks. Leveraging tried-and-true code and systems is vital, as seen in the selection of Geth as the default engine for the OP Stack. A lean codebase is crucial for both security and ease of management. Every coding line is a potential bug entry point, so concise protocols minimize risks. Plus, a streamlined codebase encourages external participation, ensuring the OP Stack's integrity.


The true essence of robust OP Stack coding is its adaptability and Extensibility. Promoting teamwork helps shun siloed development methods. United efforts mean more time for innovation and less for redundant tasks. Collaboration is our shared path to triumph. Extensible code is designed foreseeing future expansions. This involves abiding by open-source guidelines, offering intuitive interfaces, and ensuring the code's modular nature, allowing others to augment its features effortlessly. Extensibility is pivotal, igniting the full potential of collaborations within the Optimism Collective ecosystem.

OP Stack Layers

Data Availability

This layer defines where the raw inputs for an OP Stack-based chain are published. Chains on the OP Stack can use one or multiple Data Availability modules for input data access. The choice of modules significantly impacts the security model and synchronization abilities. For instance, if data becomes inaccessible, chain synchronization might be compromised, underscoring the importance of wise module selection.

Ethereum DA

Currently, the Ethereum Data Availability (DA) module is the go-to for the OP Stack. It extracts data from varied sources on the Ethereum blockchain, such as Ethereum calldata, events, and 4844 data blobs. Its widespread adoption signifies its efficiency within the Optimism ecosystem.


This layer organizes and publishes user transactions. Typically, a dedicated Sequencer entity manages sequencing in the default Rollup configuration. Established rules limit the Sequencer’s hold on transactions, ensuring timely processing. A future modular design will let chains select their Sequencing mechanism, emphasizing adaptability.

Single Sequencer

By default, the Single Sequencer is used. A designated entity becomes the Sequencer, with a transparent selection mechanism ensuring its efficient functioning.

Multiple Sequencer

An alternative to the Single Sequencer is the Multiple Sequencer, where a Sequencer is picked from a set list. This approach grants chains more control over the Sequencing process.


This layer processes raw data from the Data Availability Layer, turning it into inputs for the Execution Layer via the Ethereum Engine API. It can tailor inputs from various sources and ensures compatibility with the data provided by the Data Availability Layer.


The Rollup module pulls inputs from numerous sources like Ethereum block data and Sequencer transaction batches.

Settlement Layer

This layer facilitates third-party chains to understand an OP Stack chain’s state. Though often associated with financial withdrawals, its core purpose is to provide access to a chain’s state. Once a transaction is confirmed on the Data Availability Layer, its status becomes permanent on the OP Stack.

Attestation-based Fault Proof

This mechanism uses an optimistic protocol. Proposers suggest the perceived correct state, and if unchallenged within a timeframe, it's accepted. Challenges rely on attestations from pre-defined parties.

Fault Proof Optimistic Settlement

This mechanism is similar to the Attestation-based approach but uses a fault-proofing process instead. Its trustworthiness hinges on the reliability of the fault-proof construction.

Validity Proof Settlement

This mechanism requires a mathematical proof to affirm a state's correctness. A state is only acknowledged if a valid proof backs it.


This overarching layer manages system configuration, upgrades, and design within the OP Stack ecosystem. It wields influence across the OP Stack and serves as a hub for community-aligned decision-making.

Multi Sig Contracts

These are smart contracts activated by a specified number of signatures from a group. For instance, on Optimism Mainnet, they manage bridge contract upgrades. Their security depends on participant numbers, signature thresholds, and participant practices.

Governance Tokens

These tokens decentralize decision-making. Their functionalities vary, but typically, they enable token holders to vote on project decisions. By holding such tokens, members have a say in the project's trajectory, promoting democracy and inclusivity in the ecosystem.


Layer 2


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