OP Mainnet logoOP Mainnet

OP Mainnet is an EVM-equivalent Optimistic Rollup. It aims to be fast, simple, and secure.
Value Locked

$7.79 B

3.42%

Canonically Bridged
$4.59 B
Externally Bridged
$45.61 M
Natively Minted
$3.15 B
  • Tokens
  • Daily TPS
    5.793.90%
  • 30D tx count
    16.22 M
  • Stage
    Stage 0
  • Type
    Optimistic Rollup
  • Purpose
    Universal
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    Milestones

    OP Mainnet starts using blobs

    2024 Mar 14th

    OP Mainnet starts publishing data to blobs.

    Learn more

    Network Upgrade #5: Ecotone

    2024 Mar 14th

    Optimism adopts EIP-4844.

    Learn more

    Fault Proof System is live on OP Goerli

    2023 Oct 3rd

    Fraud Proof system is live on Goerli.

    Learn more

    Mainnet migration to Bedrock

    2023 Jun 6th

    OP Mainnet, since Jun 2023 is running Bedrock.

    Learn more

    OP Stack Introduced

    2022 Oct 17th

    OP Stack, modular, open-sourced blueprint on how to build scalable blockchains.

    Learn more

    OP token airdrop

    2022 May 31st

    The first round of OP token airdrop.

    Learn more

    Mainnet for everyone

    2021 Dec 16th

    Whitelist got removed, there are no restrictions on who can transact with the network.

    Learn more

    OVM 2.0 is live

    2021 Nov 12th

    Network upgrade to OVM 2.0 and removal of fraud-proof system.

    Learn more

    Community Launch

    2021 Aug 19th

    All smart contracts allowed after prior approval.

    Learn more

    Mainnet Soft Launch

    2021 Jan 16th

    Only selected contracts like Synthetix and Uniswap are available.

    Learn more
    Risk summary
    Fraud proof system is currently under development. Users need to trust block Proposer to submit correct L1 state roots.
    Risk analysis
    Fraud proof system is currently under development. Users need to trust block Proposer to submit correct L1 state roots.
    Sequencer failureState validationData availabilityExit windowProposer failure

    State validation

    In development

    Currently the system permits invalid state roots. More details in project overview.

    Data availability

    On chain

    All of the data needed for proof construction is published on Ethereum L1.

    Exit window

    None

    There is no window for users to exit in case of an unwanted upgrade since contracts are instantly upgradable.

    Sequencer failure

    Self sequence

    In the event of a sequencer failure, users can force transactions to be included in the project’s chain by sending them to L1. There is a 12h delay on this operation.

    Proposer failure

    Cannot withdraw

    Only the whitelisted proposers can publish state roots on L1, so in the event of failure the withdrawals are frozen.

    Rollup stage
    OP MainnetOP Mainnet is a
    Stage 0
    Optimistic Rollup.
    Stage 0
    4 requirements met
    Stage 1
    4 issues need fixing
    Stage 2
    1 issue needs fixing
    Learn more about Rollup stages
    Please keep in mind that these stages do not reflect rollup security, this is an opinionated assessment of rollup maturity based on subjective criteria, created with a goal of incentivizing projects to push toward better decentralization. Each team may have taken different paths to achieve this goal.
    Technology

    Fraud proofs are in development

    Ultimately, OP stack chains will use interactive fraud proofs to enforce state correctness. This feature is currently in development and the system permits invalid state roots.

    • Funds can be stolen if an invalid state root is submitted to the system (CRITICAL).

    1. L2OutputOracle.sol - Etherscan source code, deleteL2Outputs function

    All data required for proofs is published on chain

    All the data that is used to construct the system state is published on chain in the form of cheap blobs or calldata. This ensures that it will be available for enough time.

    1. Derivation: Batch submission - OP Mainnet specs
    2. BatchInbox - Etherscan address
    3. OptimismPortal.sol - Etherscan source code, depositTransaction function
    State derivation
    Node software

    The rollup node is composed of two software components: op-node, implementing consensus related logic, and op-geth, implementing execution logic. The configuration file can be found here.

    Compression scheme

    Data batches are compressed using the zlib algorithm with best compression level.

    Genesis state

    Since OP Mainnet has migrated from the OVM to Bedrock, a node must be synced using a data directory that can be found here. To reproduce the migration itself, see this guide.

    Data format

    The format specification of Sequencer’s data batches can be found here.

    Operator

    The system has a centralized operator

    The operator is the only entity that can propose blocks. A live and trustworthy operator is vital to the health of the system.

    • MEV can be extracted if the operator exploits their centralized position and frontruns user transactions.

    1. L2OutputOracle.sol - Etherscan source code, CHALLENGER address
    2. L2OutputOracle.sol - Etherscan source code, PROPOSER address
    3. Decentralizing the sequencer - OP Stack docs

    Users can force any transaction

    Because the state of the system is based on transactions submitted on-chain and anyone can submit their transactions there it allows the users to circumvent censorship by interacting with the smart contract directly.

    1. Sequencing Window - OP Mainnet Specs
    2. OptimismPortal.sol - Etherscan source code, depositTransaction function
    Withdrawals

    Regular exit

    The user initiates the withdrawal by submitting a regular transaction on this chain. When the block containing that transaction is finalized the funds become available for withdrawal on L1. The process of block finalization takes a challenge period of 7d to complete. Finally the user submits an L1 transaction to claim the funds. This transaction requires a merkle proof.

    • Funds can be frozen if the centralized validator goes down. Users cannot produce blocks themselves and exiting the system requires new block production (CRITICAL).

    1. OptimismPortal.sol - Etherscan source code, proveWithdrawalTransaction function
    2. OptimismPortal.sol - Etherscan source code, finalizeWithdrawalTransaction function
    3. L2OutputOracle.sol - Etherscan source code, PROPOSER check

    Forced exit

    If the user experiences censorship from the operator with regular exit they can submit their withdrawal requests directly on L1. The system is then obliged to service this request or halt all withdrawals, including forced withdrawals from L1 and regular withdrawals initiated on L2. Once the force operation is submitted and if the request is serviced, the operation follows the flow of a regular exit.

    1. Forced withdrawal from an OP Stack blockchain
    Other considerations

    EVM compatible smart contracts are supported

    OP stack chains are pursuing the EVM Equivalence model. No changes to smart contracts are required regardless of the language they are written in, i.e. anything deployed on L1 can be deployed on L2.

    1. Introducing EVM Equivalence
    Upgrades & Governance
    A diagram of the upgrades and governance
    A diagram of the upgrades and governance

    All contracts are upgradable by the ProxyAdmin which is controlled by a 2/2 multisig composed by the Optimism Foundation and a Security Council. Currently, the Guardian, the Proposer and the Challenger roles are assigned to single actors and an implementation upgrade is required to update them.

    The FoundationMultisig_2 controls both the Guardian and Challenger role. FoundationMultisig_2 controls the SuperchainConfig Superchain-wide pause mechanism that can pause L1CrossDomainMessenger messages relay, as well as ERC-20 and ERC-721 withdrawals. The single Sequencer actor can be modified by the FoundationMultisig_2 via the SystemConfig contract.

    At the moment, for regular upgrades, the DAO signals its intent by voting on upgrade proposals, but has no direct control over the upgrade process.

    Permissions

    The system uses the following set of permissioned addresses:

    ProxyAdmin 0x543b…fB04

    Owner of AddressManager. Admin of OptimismPortal, SystemConfig, L2OutputOracle, L1ERC721Bridge, OptimismMintableERC20Factory, L1StandardBridge.

    Used in:

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    Sequencer 0x6887…2985

    Central actor allowed to commit L2 transactions to L1.

    Proposer 0x4733…3A33

    Central actor allowed to post new L2 state roots to L1.

    Challenger 0x9BA6…6b3A

    Central actor allowed to delete L2 state roots proposed by a Proposer.

    Used in:

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    Guardian 0x9BA6…6b3A

    Central actor allowed to pause deposits and withdrawals.

    Used in:

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    ProxyAdminOwner 0x5a0A…3d2A

    Owner of the ProxyAdmin. It can upgrade the bridge implementation potentially gaining access to all funds, and change any system component. This is a Gnosis Safe with 2 / 2 threshold.

    Used in:

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    ProxyAdminOwner participants (2) 0x847B…9D920xc281…Bd03

    Those are the participants of the ProxyAdminOwner.

    FoundationMultisig_1 0x847B…9D92

    Member of the ProxyAdminOwner. This is a Gnosis Safe with 5 / 7 threshold.

    Used in:

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    Those are the participants of the FoundationMultisig_1.

    SecurityCouncilMultisig 0xc281…Bd03

    Member of the ProxyAdminOwner. This is a Gnosis Safe with 4 / 13 threshold.

    Used in:

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    FoundationMultisig_2 0x9BA6…6b3A

    This address is the owner of the following contracts: SystemConfig. It is also designated as a Guardian of the OptimismPortal, meaning it can halt withdrawals, and as a Challenger for state roots. This is a Gnosis Safe with 5 / 7 threshold.

    Used in:

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    Those are the participants of the FoundationMultisig_2.

    Smart contracts
    A diagram of the smart contract architecture
    A diagram of the smart contract architecture

    The system consists of the following smart contracts:

    The L2OutputOracle contract contains a list of proposed state roots which Proposers assert to be a result of block execution. Currently only the PROPOSER address can submit new state roots.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

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    The OptimismPortal contract is the main entry point to deposit funds from L1 to L2. It also allows to prove and finalize withdrawals. This contract stores the following tokens: ETH.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

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    It contains configuration parameters such as the Sequencer address, the L2 gas limit and the unsafe block signer address.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

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    The L1CrossDomainMessenger (L1xDM) contract sends messages from L1 to L2, and relays messages from L2 onto L1. In the event that a message sent from L1 to L2 is rejected for exceeding the L2 epoch gas limit, it can be resubmitted via this contract’s replay function.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

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    The L1StandardBridge contract is the main entry point to deposit ERC20 tokens from L1 to L2. This contract can store any token.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

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    The L1ERC721Bridge contract is used to bridge ERC-721 tokens from L1 to L2.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

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    The SuperchainConfig contract is used to manage global configuration values for multiple OP Chains within a single Superchain network. The SuperchainConfig contract manages the PAUSED_SLOT, a boolean value indicating whether the Superchain is paused, and GUARDIAN_SLOT, the address of the guardian which can pause and unpause the system.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Proxy used in:

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    Value Locked is calculated based on these smart contracts and tokens:

    Main entry point for users depositing ERC20 token that do not require custom gateway.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

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    Main entry point for users depositing ETH.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

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    Escrow for DAI 0x4671…6C65

    DAI Vault for custom DAI Gateway managed by MakerDAO.

    Escrow for SNX 0x5Fd7…eF9f

    SNX Vault for custom SNX Gateway managed by Synthetix.

    wstETH Vault for custom wstETH Gateway. Fully controlled by Lido governance.

    The current deployment carries some associated risks:

    • Funds can be stolen if a contract receives a malicious code upgrade. There is no delay on code upgrades (CRITICAL).

    Knowledge nuggets