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Axiom NodeJS Module

To construct an Axiom client circuit and interact with it directly in Typescript, you will need to use the Axiom class. This is not necessary if you are only using the CLI, in which case you can skip directly to the Axiom CLI Reference.

The Axiom class exposes prove and sendQuery functionality and must be used in conjunction with the Axiom CLI to first compile the circuit.

import { Axiom } from '@axiom-crypto/client';

Axiom class

The Axiom class is defined as

export class Axiom<T> {
constructor(inputs: {
circuit: (inputs: T) => Promise<void>;
compiledCircuit: AxiomV2CompiledCircuit;
chainId: string;
provider: string;
privateKey?: string;
version?: string;
callback: AxiomV2CallbackInput;

This class is generic over a type T, which is the input type of the circuit. See Data Types for Circuits for more details.

  • circuit: this is the client circuit code itself, which you write separately. The client circuit code is specified as an async function (inputs: T) => Promise<void>.
  • compiledCircuit: the JSON build output from the CLI compile function
  • chainId: the chain ID the on-chain data is gotten from. Only used for computation of sendQueryArgs. Does not affect circuit compilation or runs.
  • provider: the JSON-RPC URL provider, this is used to make RPC calls to get on-chain data values (that are not ZK-verified)
  • callback:
    • target: the target contract address with the callback function
    • extraData: optional parameter to specify hex string of bytes for any extra data to pass to the callback

The functions in the Axiom class are:


async init()

Initializes the circuit using the compiled build artifacts specified in the constructor.


setOptions(options: {
maxFeePerGas?: string;
caller?: string;
callbackGasLimit?: number;
overrideAxiomQueryFee?: string;
refundee?: string;

Set options used to build the query.

  • maxFeePerGas: optional argument to set maxFeePerGas, in wei, for Axiom to use on the fulfillment and callback transaction. Default is fetched from provider.getFeeData() at runtime.
  • caller: optional argument for the sender address, only used for queryId calculation
  • callbackGasLimit: optional argument to set the gas limit for the callback function. Default is 200000 gas.
  • overrideAxiomQueryFee: optional argument to specify a higher query fee, in wei.
  • refundee: address to refund payment to. Defaults to caller.


setCallback(callback: {
target?: string;
extraData?: string;

Set configuration options for the callback contract.

  • target: the target contract address with the callback function and the
  • extraData: optional parameter to specify hex string of bytes for any extra data to pass to the callback


async prove(input: RawInput<T>): Promise<AxiomV2SendQueryArgs>

Runs the circuit to generate a client-side ZK proof. The same circuit can be run on multiple different inputs.

  • input: this is any type that can be parsed into the predefined circuit input type T
    • This will fail at runtime if, for example, you try to parse a hex string representing uint256 into CircuitValue

The return type of prove is the AxiomV2SendQueryArgs interface:

address: string,
abi: any,
functionName: string = "sendQuery",
value: bigint,
args: Array<any>,
queryId: string,
calldata: string
  • address: the AxiomV2Query address, calculated based on AxiomCircuit constructor arguments
  • abi: the ABI of the AxiomV2Query contract
  • functionName: always equals sendQuery (the function name on the callback contract)
  • value: suggested payment value in wei, auto-calculated based on gas fees and costs
  • args: the array of arguments to pass into the sendQuery function call, formatted exactly as it would be used in ethers-js or viem.
    • args = [sourceChainId, dataQueryHash, computeQuery, callback, salt, maxFeePerGas, callbackGasLimit, refundAddress, dataQuery]
  • queryId: the unique identifier for this query, including user information such as caller and callback address.
    • For this to match the queryId calculated on-chain, the input callerAddress must match the actual transaction sender address
  • calldata: the hex string of the args encoded with sendQuery function selector. You can send a sendQuery transaction directly using this calldata.


async sendQuery(args: AxiomV2SendQueryArgs): Promise<TransactionReceipt>

Sends a query from args generated by prove. Requires that a private key was set in the Axiom constructor. To use your own signer, you can use ethers-js or viem to send a query using output of prove.