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Gas, Pricing, and Limits

Axiom charges fees and verifies proofs on-chain via the AxiomV2Query contract, which manages balances, tracks query state, and escrows/unescrows ETH from your balance as queries are requested and fulfilled.

Fulfillment Gas and Pricing​

The fulfillment cost of an Axiom query includes:

  • gas for on-chain verification of the final ZK proof generated by Axiom
  • gas to trigger the final smart contract callback
  • a fee charged by Axiom on a per-query basis

Axiom passes through gas costs to the user and collects an additional fee for each query. The AxiomV2Query contract escrows funds for each query from your balance to ensure that you can cover the payment. This maximum query price is calculated on mainnet as

maxQueryPri = maxFeePerGas * (callbackGasLimit + proofVerificationGas) + axiomQueryFee;

and on L2s as

maxQueryPri = maxFeePerGas * (callbackGasLimit + proofVerificationGas) + overrideAxiomQueryFee;

The parameters set by Axiom are:

  • proofVerificationGas: The gas cost of ZK proof verification, currently set to 420_000 gas
  • axiomQueryFee: Fee charged by Axiom, fixed to 0.003 ether

The parameters set by the user for each query are:

  • maxFeePerGas: The max fee per gas that the prover should use in the fulfill query transaction.
  • callbackGasLimit: The gas limit allocated for use in the callback.

If either of these parameters is too low, the fulfill query transaction cannot be sent successfully. Prior to query fulfillment, the user can update the parameters maxFeePerGas and callbackGasLimit by calling the increaseQueryGas function.

The AxiomV2Query contract will escrow maxQueryPri from the user's balance for a query. This is the maximum cost of fulfilling the query. After the prover has fulfilled the query, they can refund any portion of the maxQueryPri not used in gas or the axiomQueryFee back to the refundee specified in the query. The refund is sent to the user's balance.

Query Limits​

We can support much larger queries on a partnership basis. If you are interested in larger queries, fill out the Axiom partner form to explore an integration.

For the Axiom V2 mainnet release, an Axiom query has the following limits:

  • The axiomResults: bytes32[] sent in the callback can have length at most 128.
  • There can be at most 128 total subqueries in the query.

These are the only limits when there are no subqueries of the following types:

  • Transaction subquery for a transaction with more than 8192 bytes of input data or more than 4096 bytes in the RLP encoded access list.
  • Receipt subquery for a transaction receipt with either more than 80 logs or which contains a log with data field exceeding 1024 bytes.

For these larger transaction and receipt subqueries, we have more fine-grained limits. These are detailed in the Transaction Subquery and Receipt Subquery sections of the Axiom Typescript SDK documentation. We expect limits on Base to be similar, but will finalize them upon our Base mainnet release.

Deposit and Withdraw​

You can deposit ETH into the AxiomV2Query contract by calling the deposit function or by transferring ETH together with your on-chain query. You can withdraw from your unescrowed balance by calling the withdraw function.

Refunds​

If a query is not fulfilled by deadlineBlockNumber, the refundee specified in the query can retrieve their fees paid using the refundQuery function.

The deadlineBlockNumber is set to queryDeadlineInterval blocks after query submission. Currently the value of queryDeadlineInterval is:

7200 blocks (approximately 1 day)