Skip to content

Chain · checked 9 November 2026

Agent payment safety checks for OP Mainnet

OP Mainnet is the flagship OP Stack L2, where an agent pays an L1 data fee on top of gas and relies on L1 forced inclusion if the sequencer stalls.

What your agent needs to know about OP Mainnet

Finality
OP Stack docs describe unsafe, safe and finalized heights. If the sequencer cannot publish to L1, the safe and finalized heights stall while unsafe keeps rising, and an extended stall can force the L2 chain to reorganize. Treat a payment as final only when it is under the finalized height. The docs give no single OP Mainnet time for batch finality, so none is stated here. For a total sequencer outage, users can call depositTransaction on the chain's OptimismPortal on L1, and the transaction must be included within the sequencer window (12 hours by default, can differ by chain), or the chain reorganizes to include it.[1]
Fees
Total fee is gas used times (base fee plus priority fee), plus the L1 data fee, plus an operator fee after Isthmus. The L1 data fee is the only part that differs from Ethereum, is charged automatically, cannot currently be capped, and moves with Ethereum base fee and blob base fee. Since Ecotone, batches can be posted as blobs, so the blob base fee drives the L1 fee. Fee vaults collect all components; nothing is burned. The gas token is ETH.[2]
Stablecoins
Circle lists native USDC on OP Mainnet at the address below. Circle's Bridged USDC Standard pages describe bridged USDC as third party issued and not CCTP compatible; the OP docs describe an in-place upgrade path to native USDC by agreement with Circle. The OP docs do not say which OP Mainnet token is USDC.e, so check the address against Circle's list. Tether's page did not list Optimism, so no USDT address is given.[3],[4],[5]
Issuer-published contract addresses. Compare all of it, not the first and last characters.
TokenAddressSource
USDC (native, Circle)0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85[3]

How agent payments go wrong on OP Mainnet

  1. 1. Uncapped L1 data fee

    The L1 data fee cannot be capped by the sender and follows Ethereum gas and blob prices. An agent with a hard fee ceiling can overspend or have a transaction fail. Estimate L2 plus L1 together right before signing.[2]

  2. 2. Safe and finalized heights stall

    If the sequencer cannot publish to L1, unsafe keeps rising while safe and finalized stop. An agent that only watches unsafe will treat payments as done that may later be reorganized. Check the finalized tag before releasing value.[1]

  3. 3. Sequencer outage up to the sequencer window

    In a total outage, forced inclusion through the L1 OptimismPortal can take up to the sequencer window (12 hours by default). The agent should time out, alert and avoid double sending.[1]

  4. 4. Bridged USDC taken for native

    Bridged USDC is not issued by Circle and is not CCTP compatible. Accept only the address Circle lists for OP Mainnet.[3],[4]

  5. 5. Aliased sender address from L1 contracts

    Contracts that call the L1 portal appear on L2 under an aliased address. An agent that matches an expected sender address for forced transactions must account for the alias.[1]

Pre-flight checklist for a OP Mainnet agent

  • Accept USDC only at Circle's native OP Mainnet address.
  • Estimate total fee including the L1 data fee before signing.
  • Use the finalized height before releasing high-value goods.
  • Alert and stop retries if safe and finalized heights stop advancing.
  • Call isBlacklisted on the USDC contract for the payee before sending.

Run the checks now, free

The free tools run in your browser: nothing you type leaves your browser, and wallet reads go only to a public RPC.

  • The Wrong-Money Test

    Write down what happens when your agent pays the wrong amount, the wrong address or the wrong token on OP Mainnet, and see whether the answer holds up.

  • Agent Spend-Cap Stress Test

    Work out how much your agents can really move in one window once retries, parallel runs and per-key limits stack up.

  • Agent Money Trace

    Reads an address's OP Mainnet stablecoin transfers from a public RPC and joins them to your run log: orphan spend, phantom successes and double pays.

Want a second pair of eyes on how your agent pays on OP Mainnet? Book the free 48-hour integration review (opens Cal.com in a new tab).

Explorers to confirm a payment

Sources

  1. [1] OP Stack rollup outages, Optimism docs
  2. [2] OP Stack transaction fees, Optimism docs
  3. [3] USDC contract addresses, Circle
  4. [4] Bridged USDC Standard, Circle
  5. [5] Bridged USDC Standard (OP Stack), Optimism docs

Checked against these sources on 9 November 2026. Networks change: confirm against the live docs before you rely on a number. This page is a checklist from public documentation. It is not a security audit, legal, compliance or investment advice.