The evolution of the OP Stack and the Superchain

The transition from the original OVM to the modular OP Stack began in 2021 when developers replaced a 6,000-line transpiler with a 300-line modification to the Solidity compiler that took only a few days to implement. In 2021, the team decided to abandon the original OVM design in favor of a modular approach that separated execution from proving, a move that resulted in an EVM equivalence upgrade that still holds its own against the latest releases from alternative rollups. The Bedrock upgrade implemented a modular architecture that separates consensus, execution, and settlement. This design reduced the code required to implement an alternate client to 1,000 lines. The upgrade also introduced a 2-phase withdrawal process to increase bridge security. This overhaul achieved a 47% reduction in protocol costs and security fees.

The OP Stack Architecture

The OP Stack relies on specific modules to function. The execution engine uses op-geth, which is a modified version of the Ethereum Geth client. The op-node handles the rollup node functions, including the sequencer and verifier roles. The op-batcher submits transaction batches to the BatchInbox on Ethereum. The op-proposer sends the output root to the L2OutputOracle. The op-challenger manages the fault proof process. These modules coordinate to ensure the security and performance of the network.

The Rollup-node operates in two modes. In sequencer mode, it creates blocks using the Engine API. In verifier mode, it compares the locally generated output root with the root in the L2OutputOracle. The BatchInbox acts as the L1 address where the sequencer stores transaction batches. The OptimismPortal manages L1 deposits and withdrawals. The sequencer sends data to the execution engine to incorporate new blocks into the L2 chain.

Superchain Growth and the Base Migration

The Superchain architecture links multiple chains like Base, World Chain, Mode, Zora, and Sonic. These chains share standards, governance, and interoperability. The Superchain now includes 50 chains. In Q4 2025, Base generated $19M in gross sequencer revenue. After accounting for L1 data costs and the OP Collective revenue share, net Base revenue was $15M for the quarter. The Superchain faces a concentration risk because Base announced its migration off the OP Stack in February 2026. You already know the basics of rollups, so focus on how sequencer revenue feeds the Collective. Can the Superchain maintain its scale if more large chains follow the decision made by Base?

Governance and the OP Token

The OP token governs the Optimism Collective through the Token House and Citizens’ House. It has a total supply of 4,294,967,296 OP and a 2% annual inflation rate. The Collective uses the token for Retroactive Public Goods Funding. In January 2026, governance approved a program to direct 50% of net Superchain sequencer revenue toward OP buybacks over a 12-month pilot. This program aligns the token with network usage. The buyback program remains subject to the 343 million OP scheduled to unlock between May 2026 and April 2027.