OP Stack
OP Stack
OP Stack is Optimism's open-source, modular framework for building Layer 2 blockchains. It powers OP Mainnet and is the shared codebase underlying the superchain — a growing network of L2s that share security, tooling, and interoperability protocols.
Notable development (February 2026): Base announced it is departing the OP Stack ecosystem, migrating to a proprietary "unified stack." This is the first major Superchain chain to leave, and signals potential divergence in the optimistic rollup ecosystem.
Architecture
OP Stack decomposes a chain into discrete layers, each swappable:
- Execution layer — EVM-equivalent transaction processing; uses op-geth (a fork of go-ethereum)
- Consensus layer — op-node (the rollup driver) drives block derivation from L1 data; the sequencer produces blocks
- Data availability layer — by default posts transaction data to Ethereum via op-batcher (posts batched transactions to L1 via blobs); can be swapped for data-availability alternatives like Celestia
- Settlement layer — dispute game contracts on Ethereum L1 handle fault proofs and finality
- Governance layer — upgrades controlled by the Security Council and Optimism governance
Chains are deployed and upgraded using op-deployer, the official CLI tool for deploying and upgrading OP Stack contracts.
Fault Proofs
OP Stack's fault proof system went live on OP Mainnet on June 10, 2024 — the first OP Stack chain to achieve this. Dispute games allow any party to challenge an invalid output root on-chain. OP Mainnet, Base, and several other chains are now classified as Stage 1 rollups with live, permissionless fraud proof systems.
Who's Using It
- base — Coinbase's L2, largest by activity in the Superchain (departing February 2026)
- Zora — NFT-focused chain
- Mode — DeFi-oriented OP chain
- World Chain — Worldcoin's identity-gated L2
- Unichain — Uniswap's own execution environment
- INK — Kraken-backed L2
- Soneium — Sony's chain
As of early 2026, the OP Stack powers more production chains than any other rollup framework, though Base's departure is a significant development to watch.
Key Numbers
- op-deployer v0.6.0 (March 2026) supports contract suite v6.0.0 ("u18")
- Base alone generated $78.2M in network revenue in 2025
Tradeoffs
OP Stack uses optimistic execution — transactions are assumed valid unless challenged. This gives ~7-day withdrawal delays to L1. ZK-based stacks (rollups) eliminate this delay but carry higher proving costs and complexity.
Related
optimism · superchain · rollups · base · data-availability