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  "schemaVersion": "1.0.0",
  "id": "optimism-op-mainnet",
  "canonical": "https://degreesofsatoshi.com/encyclopedia/optimism-op-mainnet/",
  "collection": "ethereum",
  "title": "What is OP Mainnet? The chain, the OP Stack and its settlement",
  "description": "Understand OP Mainnet’s OP Stack rollup structure and how sequencer inclusion, safe blocks and finalized blocks differ.",
  "aliases": [
    "OP Mainnet explained",
    "Optimism network OP Stack"
  ],
  "dates": {
    "published": "2026-10-02",
    "modified": "2026-10-02",
    "verified": "2026-10-02T19:27:58.939Z",
    "dataAsOf": "2026-10-02"
  },
  "authorship": {
    "publisher": "Degrees of Satoshi editorial project",
    "process": "AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied."
  },
  "quickAnswer": {
    "text": "OP Mainnet is an Ethereum rollup built with the OP Stack. The sequencer can include a transaction quickly, then the chain’s data is published to Ethereum and becomes finalized with the relevant Ethereum chain state. These stages are distinct from a standard-bridge withdrawal, which also requires proving and finalizing a message on Ethereum.",
    "claimId": "optimism-op-mainnet-quick-answer",
    "sourceIds": [
      "x425-eth-op-intro",
      "x425-eth-op-finality",
      "x425-eth-op-withdrawals"
    ]
  },
  "keyFacts": [
    {
      "label": "Software",
      "value": "OP Stack supplies the software used by OP Mainnet.",
      "sourceIds": [
        "x425-eth-op-intro"
      ],
      "id": "software",
      "claimId": "optimism-op-mainnet-fact-software"
    },
    {
      "label": "Unsafe head",
      "value": "The protocol calls sequencer blocks not yet backed by published data unsafe.",
      "sourceIds": [
        "x425-eth-op-finality"
      ],
      "id": "unsafe-head",
      "claimId": "optimism-op-mainnet-fact-unsafe-head"
    },
    {
      "label": "Withdrawal",
      "value": "The documented withdrawal flow separates initiate, prove and finalize.",
      "sourceIds": [
        "x425-eth-op-withdrawals"
      ],
      "id": "withdrawal",
      "claimId": "optimism-op-mainnet-fact-withdrawal"
    }
  ],
  "prerequisites": [
    "optimistic-rollups",
    "rollup-sequencers"
  ],
  "sections": [
    {
      "id": "stages",
      "heading": "Read the meaning behind the confirmation label",
      "sourceIds": [
        "x425-eth-op-finality"
      ],
      "paragraphs": [
        "A sequencer acknowledgment offers an early result with sequencer-related assumptions. A safe block has the required data included on Ethereum; finalized reflects finality of the relevant Ethereum data. These names are protocol status labels, not ratings of an application’s honesty.",
        "An application can choose to act before the strongest stage, but that choice should match its risk tolerance and state-reconciliation design."
      ]
    },
    {
      "id": "example",
      "heading": "A swap does not wait for the bridge withdrawal period",
      "sourceIds": [
        "x425-eth-op-finality",
        "x425-eth-op-withdrawals"
      ],
      "paragraphs": [
        "Suppose you swap tokens entirely on OP Mainnet. Its chain-inclusion and finality stages are not the same workflow as withdrawing those tokens to Ethereum. The standard bridge’s waiting conditions apply to the cross-chain withdrawal claim.",
        "Do not interpret a bridge delay as a rule that every OP Mainnet transaction remains reversible for that entire period."
      ]
    },
    {
      "id": "configuration",
      "heading": "An OP Stack chain is a specific deployment",
      "sourceIds": [
        "x425-eth-op-intro",
        "x425-eth-op-finality"
      ],
      "paragraphs": [
        "OP Stack is reusable software, while OP Mainnet is a particular network. Other deployments can choose different settings or modify components. Check chain identity, supported assets and current upgrade configuration when moving between them.",
        "This description follows the standard rollup configuration documented on 2 October 2026 and does not assert that all chains carrying the OP Stack label have identical guarantees."
      ]
    }
  ],
  "faq": [
    {
      "question": "Does unsafe mean the transaction is necessarily fraudulent?",
      "answer": "No. It is the protocol label for a sequencer block whose data has not yet reached the later Ethereum-backed stage. It does not evaluate the application.",
      "sourceIds": [
        "x425-eth-op-finality"
      ]
    },
    {
      "question": "Does a finalized OP Mainnet transaction mean an Ethereum withdrawal is paid?",
      "answer": "No. A cross-chain withdrawal has additional proof and finalization steps on L1. Check its own completion state.",
      "sourceIds": [
        "x425-eth-op-finality",
        "x425-eth-op-withdrawals"
      ]
    }
  ],
  "claims": [
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      "statement": "OP Mainnet is an Ethereum rollup built with the OP Stack. The sequencer can include a transaction quickly, then the chain’s data is published to Ethereum and becomes finalized with the relevant Ethereum chain state. These stages are distinct from a standard-bridge withdrawal, which also requires proving and finalizing a message on Ethereum.",
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          "locator": "OP Stack; components; deployments"
        },
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          "sourceId": "source-543974e486aeb01b",
          "locator": "Unsafe; safe; finalized; withdrawal distinction"
        },
        {
          "sourceId": "source-78235bf07c29d69c",
          "locator": "Initiate; prove; finalize; fault proofs"
        }
      ],
      "scope": {
        "collection": "ethereum",
        "dataAsOf": "2026-10-02",
        "blockHeight": null
      },
      "qualification": "",
      "evidenceStatus": "documented",
      "verification": {
        "status": "verified",
        "method": "independent automated source review",
        "checkedAt": "2026-10-02T19:27:58.939Z",
        "reviewer": "Independent automated verification agent verify_bitcoin_stablecoins_100",
        "notes": [
          "Read OP Stack introduction, complete finality guide and withdrawal flow. Unsafe/safe/finalized terms describe sequencing and Ethereum publication, not app legitimacy. Standard-bridge waiting is distinct from ordinary L2 finality; configuration scope explicit and generic absolute source reassurance not copied."
        ]
      }
    },
    {
      "id": "optimism-op-mainnet-fact-software",
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      "evidenceStatus": "documented",
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        "notes": [
          "Read OP Stack introduction, complete finality guide and withdrawal flow. Unsafe/safe/finalized terms describe sequencing and Ethereum publication, not app legitimacy. Standard-bridge waiting is distinct from ordinary L2 finality; configuration scope explicit and generic absolute source reassurance not copied."
        ]
      }
    },
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          "locator": "Unsafe; safe; finalized; withdrawal distinction"
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        "notes": [
          "Read OP Stack introduction, complete finality guide and withdrawal flow. Unsafe/safe/finalized terms describe sequencing and Ethereum publication, not app legitimacy. Standard-bridge waiting is distinct from ordinary L2 finality; configuration scope explicit and generic absolute source reassurance not copied."
        ]
      }
    },
    {
      "id": "optimism-op-mainnet-fact-withdrawal",
      "articleSlug": "optimism-op-mainnet",
      "statement": "Withdrawal: The documented withdrawal flow separates initiate, prove and finalize.",
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      "sourceLocators": [
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          "sourceId": "source-78235bf07c29d69c",
          "locator": "Initiate; prove; finalize; fault proofs"
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        "notes": [
          "Read OP Stack introduction, complete finality guide and withdrawal flow. Unsafe/safe/finalized terms describe sequencing and Ethereum publication, not app legitimacy. Standard-bridge waiting is distinct from ordinary L2 finality; configuration scope explicit and generic absolute source reassurance not copied."
        ]
      }
    }
  ],
  "sources": [
    {
      "id": "x425-eth-op-intro",
      "label": "OP Stack overview",
      "publisher": "Optimism",
      "url": "https://docs.optimism.io/stack/getting-started",
      "locator": "OP Stack; components; deployments",
      "note": "Reusable rollup software and chain-specific configuration.",
      "version": "Documentation snapshot retrieved 2 October 2026; response hash recorded separately",
      "checkedAt": "2026-10-02T18:55:27.607Z",
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    {
      "id": "x425-eth-op-finality",
      "label": "OP Stack transaction finality",
      "publisher": "Optimism",
      "url": "https://docs.optimism.io/stack/transactions/transaction-finality",
      "locator": "Unsafe; safe; finalized; withdrawal distinction",
      "note": "Sequencer acknowledgment and Ethereum-backed finality are separate stages.",
      "version": "Documentation snapshot retrieved 2 October 2026; response hash recorded separately",
      "checkedAt": "2026-10-02T18:55:27.605Z",
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    {
      "id": "x425-eth-op-withdrawals",
      "label": "OP Stack withdrawal flow",
      "publisher": "Optimism",
      "url": "https://docs.optimism.io/stack/transactions/withdrawal-flow",
      "locator": "Initiate; prove; finalize; fault proofs",
      "note": "L2-to-L1 withdrawals require distinct onchain stages and protocol waits.",
      "version": "Documentation snapshot retrieved 2 October 2026; response hash recorded separately",
      "checkedAt": "2026-10-02T18:55:27.608Z",
      "contentSha256": "445bbe7491370f3ca29ea4b597dcc3c10376c9d98a7415617f67df6267c31f51",
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  ],
  "related": {
    "articles": [
      "optimistic-rollups",
      "rollup-sequencers",
      "ethereum-proof-of-stake-finality",
      "arbitrum-one",
      "zksync-era"
    ],
    "dossiers": [],
    "wallets": []
  },
  "revisionHistory": [
    {
      "date": "2026-10-02",
      "kind": "published",
      "summary": "First publication after primary-source research and separate automated verification."
    }
  ],
  "citation": "Degrees of Satoshi editorial project. “What is OP Mainnet? The chain, the OP Stack and its settlement.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/optimism-op-mainnet/"
}