Smart Contract Call

Use the Tachyon Relay API to interact with smart contracts across multiple blockchains. The /api/submit-tx endpoint supports EVM, Solana, Aptos, Sui, and NEAR, enabling a unified interface for submitting encoded contract calls through the Tachyon network.

Chain Examples

EVM Chains (Ethereum, Base, Polygon, etc.)

SDK

Using Tachyon SDK (TypeScript)

Code Example

smart-contract-call.ts


  import { Tachyon, ChainId } from '@rathfi/tachyon';
  import { ethers } from 'ethers';
 
  // Initialize SDK
  const tachyon = new Tachyon({ apiKey: 'YOUR_API_KEY' });
 
  // Create and encode the function call
  const abi = ["function sayHello(string message)"];
  const iface = new ethers.Interface(abi);
  const callData = iface.encodeFunctionData("sayHello", ["Hello from Tachyon!"]);
 
  // Relay transaction
  const txId = await tachyon.relay({
    chainId: ChainId.BASE,
    to: "0xA7A833e6641D7901F30EaD6f27d4Ee2C9bb670a7",
    value: "0",
    callData,
    label: "Say Hello Example"
  });
 
  console.log("Transaction ID:", txId);

Step-by-Step Instructions

Install the required dependencies:

terminal


  npm install @rathfi/tachyon ethers

Import the necessary modules:
- Import Tachyon and ChainId from @rathfi/tachyon
- Import ethers for encoding contract call data
Initialize the Tachyon SDK:
- Create a new Tachyon instance
- Pass your API key in the configuration object: { apiKey: 'YOUR_API_KEY' }
Define your contract ABI:
- Create an array with the function signature(s) you want to call
- Example: ["function sayHello(string message)"]
Encode the function call:
- Create an ethers Interface instance with your ABI
- Use encodeFunctionData() to encode the function name and parameters
- Store the result in callData
Submit the relay transaction:
- Call tachyon.relay() with the transaction parameters
- Use await since this is an asynchronous operation
Handle the transaction ID:
- The method returns a txId string
- Use this ID to track the transaction status through the Tachyon API

SDK Function Parameters

tachyon.relay(options)

Parameter	Type	Required	Description	Example
`chainId`	`ChainId` or `number`	Yes	Chain identifier (use ChainId enum or number)	`ChainId.BASE` or `8453`
`to`	`string`	Yes	Target contract address	`"0xA7A833e6641D7901F30EaD6f27d4Ee2C9bb670a7"`
`value`	`string`	Yes	Amount in wei	`"0"`
`callData`	`string`	Yes	Encoded function call data	Result from `iface.encodeFunctionData()`
`label`	`string`	Optional	Custom transaction label	`"Say Hello Example"`
`gasLimit`	`string`	Optional	Gas limit override	`"100000"`
`isAuthenticatedTx`	`boolean`	Optional	Authenticated relay mode	`true` or `false`
`transactionType`	`string`	Optional	Processing type	`"flash"` or `"flash-blocks"`

Returns: Promise<string> - The transaction ID (txId)

REST API

Using REST API

Code Example

terminal


curl -X POST https://api.tachyon.rath.fi/api/submit-tx \
  -H "apikey: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "chainId": 8453,
    "to": "0xA7A833e6641D7901F30EaD6f27d4Ee2C9bb670a7",
    "value": "0",
    "callData": "0xc3a9b1c50000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000001348656c6c6f2066726f6d2054616368796f6e2100000000000000000000000000",
    "label": "Hello From Tachyon Call"
  }'

Response:

response.json


{ "txId": "68fa3450539a3c9d28bbca33" }

Step-by-Step Instructions

Obtain your API key from the Tachyon dashboard at https://api.tachyon.rath.fi
Prepare your contract call data:
- Identify the target contract address (to)
- Encode your function call into callData (see SDK example for encoding details)
- Determine the chainId for your target network (e.g., 8453 for Base, 1 for Ethereum)
Set the transaction value:
- Use "0" for non-payable functions
- Specify the amount in wei as a string for payable functions
Make the API request:
- Send a POST request to https://api.tachyon.rath.fi/api/submit-tx
- Include your API key in the api-key header as YOUR_API_KEY
- Set Content-Type header to application/json
Handle the response:
- Extract the txId from the response
- Use this txId to track your transaction status

API Parameters

The RelayParams object defines the parameters required when calling the relay() method.

Name	Type	Required	Description
`chainId`	`number`	Yes	The blockchain network ID where the transaction will be executed. Must be a supported chain.
`to`	`string`	Yes	The recipient wallet address or smart contract address. Format varies by chain (hex for EVM, base58 for Solana, named for NEAR).
`callData`	`string`	Yes	Encoded transaction data in hexadecimal format (use ‘0x’ for simple transfers).
`value`	`string`	No	Amount of native currency to send in the smallest unit (wei for EVM, lamports for Solana, yoctoNEAR for NEAR). Defaults to ‘0’ if not specified.
`label`	`string`	No	Optional human-readable label for easier transaction identification and tracking.
`gasLimit`	`string`	No	Optional gas limit for the transaction. If not specified, it will be estimated automatically.
`gasPrice`	`string`	No	Gas price for legacy transactions. Cannot be used with `maxFeePerGas` or `maxPriorityFeePerGas`.
`maxFeePerGas`	`string`	No	Maximum fee per gas for EIP-1559 transactions. Must be used together with `maxPriorityFeePerGas`.
`maxPriorityFeePerGas`	`string`	No	Maximum priority fee per gas for EIP-1559 transactions. Must be used together with `maxFeePerGas`.
`maxUSD`	`number`	No	Maximum cost in USD that you’re willing to pay for this transaction.
`retries`	`number`	No	Number of retry attempts for the transaction. Defaults to 0.
`shouldBatchInMulticall`	`boolean`	No	Whether to batch this transaction in a multicall operation.
`isAuthenticatedTx`	`boolean`	No	Enable authenticated relay mode for additional security and verification. Defaults to false.
`derivationPath`	`string`	No	Optional HD wallet derivation path for transaction signing (useful for multi-account setups).
`transactionType`	`"flash" \| "authenticated" \| "funding-signed" \| "flash-blocks"`	No	Type of relay transaction. Defaults to `"flash"`. `"flash-blocks"` is only supported on Base (8453) and Base Sepolia (84532).
`authorizationList`	`AuthorizationListItem[]`	No	Optional list of authorization entries for delegated transactions or batched operations. Cannot be used with `"flash-blocks"` transaction type.

Aptos

SDK

Using Tachyon SDK

Code Example

aptos-contract-call.ts


import { Tachyon } from '@rathfi/tachyon';
 
const tachyon = new Tachyon({ apiKey: 'YOUR_API_KEY' });
 
const functionPayload = {
  function: "0x3690a8173c5f738234d3772621db2923cf283029d0b9a7795038fde6f3fcdabd::hello_tachyon_v2::preview_message",
  typeArguments: [],
  functionArguments: ["GM Tachyon!"]
};
 
const callData = Buffer.from(JSON.stringify(functionPayload)).toString('base64');
 
const txId = await tachyon.relay({
  chainId: 88888888,
  to: "0x3690a8173c5f738234d3772621db2923cf283029d0b9a7795038fde6f3fcdabd",
  value: "0",
  callData,
  label: "send-to-aptos",
  gasLimit: "5000"
});

Solana

SDK

Using Tachyon SDK

Code Example

solana-contract-call.ts


import { Tachyon, ChainId } from '@rathfi/tachyon';
 
const tachyon = new Tachyon({ apiKey: 'YOUR_API_KEY' });
 
// 1. Create callData
const programId = "MemoSq4gqABAXKb96qnH8TysNcWxMyWCqXgDLGmfcHr";
const payer = "3dQFssz4XLF9LKTTGrqCy4PwDSFiw6QrPwHW5QkvLmw3"; // your wallet pubkey
const memoMessage = "Hello from rath";
 
// Encode the message as bytes
const instructionData = Buffer.from(memoMessage, "utf8");
 
// Build the instruction JSON
const message = {
  programId,
  keys: [],
  data: instructionData.toString("base64"),
};
 
// Encode the JSON to Base64
const callData = Buffer.from(JSON.stringify(message), "utf8").toString("base64");
 
// 2. relay contract call
const txId = await tachyon.relay({
  chainId: 10100000,
  to: "MemoSq4gqABAXKb96qnH8TysNcWxMyWCqXgDLGmfcHr",
  value: "0",
  callData,
  label: "contract-call-solana"
});

Step-by-Step Instructions

Solana SDK integration documentation will be added soon.

SDK Function Parameters

Parameters specific to Solana program calls will be documented upon release.

Sui

SDK

Using Tachyon SDK

Code Example

sui-contract-call.ts


import { Tachyon } from '@rathfi/tachyon';
import { Transaction as SuiTransaction } from '@mysten/sui/transactions';
 
const PACKAGE_ID = '0xb4ce9c7b45e665ec8a310b7f5507123fa3de79f53917f20b9408cdcb159dcc70';
 
const tx = new SuiTransaction();
 
tx.moveCall({
    target: `${PACKAGE_ID}::greeting::new`,
    arguments: [],
});
 
const txBytes = tx.serialize();
const createGreetingCallData = Buffer.from(txBytes).toString('base64');
 
const tachyon = new Tachyon({ apiKey: 'YOUR_API_KEY' });
 
const txId = await tachyon.relay({
  chainId: 897796746,
  to: "0xb4ce9c7b45e665ec8a310b7f5507123fa3de79f53917f20b9408cdcb159dcc70",
  value: "0",
  callData: createGreetingCallData,
  label: "call-contract-sui",
  gasLimit: "1000000"
});

REST API

Using REST API

Code Example

terminal


curl -X POST https://api.tachyon.rath.fi/api/submit-tx \
  -H "apikey: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "chainId": 897796746,
    "to": "0xb4ce9c7b45e665ec8a310b7f5507123fa3de79f53917f20b9408cdcb159dcc70",
    "value": "0",
    "callData": "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",
    "label": "call-contract-sui",
    "gasLimit": "1000000"
  }'

Response:

response.json


{ "txId": "68fa3450539a3c9d28bbca33" }

callData Structure (before Base64 encoding)

sui-transaction.json


{
  "version": 1,
  "expiration": null,
  "gasConfig": {},
  "inputs": [
    {
      "kind": "Input",
      "type": "object",
      "index": 0,
      "value": "0x97e01832cc80b850a159be0fcc680cd8fa6fedb232b4beb6f18c28b8a96c179c"
    },
    {
      "kind": "Input",
      "index": 1,
      "value": {"Pure": [19, 72, 101, 108, 108, 111, 32, 102, 114, 111, 109, 32, 84, 97, 99, 104, 121, 111, 110, 33]},
      "type": "pure"
    }
  ],
  "transactions": [
    {
      "kind": "MoveCall",
      "target": "0xb4ce9c7b45e665ec8a310b7f5507123fa3de79f53917f20b9408cdcb159dcc70::greeting::update_text",
      "typeArguments": [],
      "arguments": [
        {"kind": "Input", "type": "object", "index": 0, "value": "0x97e01832cc80b850a159be0fcc680cd8fa6fedb232b4beb6f18c28b8a96c179c"},
        {"kind": "Input", "index": 1, "value": {"Pure": [19, 72, 101, 108, 108, 111, 32, 102, 114, 111, 109, 32, 84, 97, 99, 104, 121, 111, 110, 33]}, "type": "pure"}
      ]
    }
  ]
}

NEAR

SDK

Using Tachyon SDK

Code Example

near-contract-call.ts


import { Tachyon } from '@rathfi/tachyon';
 
const tachyon = new Tachyon({ apiKey: 'YOUR_API_KEY' });
 
const methodCall = {
  methodName: "set_greeting",
  args: {
    greeting: "Hello from tachyon!"
  }
};
 
const callData = Buffer.from(JSON.stringify(methodCall)).toString('base64');
 
const txId = await tachyon.relay({
  chainId: 7777777,
  to: "rathgreeting.near",
  value: "0",
  callData,
  label: "contract-call-near"
});

Starknet

SDK

Using Tachyon SDK (TypeScript)

Code Example

smart-contract-call.ts


  import { CallData, CairoByteArray } from "starknet";
 
  /**
  * Script to create calldata for say_hello function in Starknet contract
  * Contract: 0x038f1247ea37e673b432794cfa8ebf4561abd0acb98ba4d726e2d15998a9013e
  * Function: say_hello(name: ByteArray) -> ByteArray
  */
 
  // Create call object for say_hello function
  function createCallObject(contractAddress, name) {
      const nameEncoded = new CairoByteArray(name);
      const calldata = CallData.compile([
          ...nameEncoded.toApiRequest(),
      ]);
      
      return [
          {
              contractAddress: contractAddress,
              entrypoint: 'say_hello',
              calldata,
          },
      ];
  }
 
  // Encode to base64 for API
  function encodeCallDataToBase64(contractAddress, name) {
      const callObject = createCallObject(contractAddress, name);
      const jsonString = JSON.stringify(callObject);
      return Buffer.from(jsonString, 'utf8').toString('base64');
  }
 
  // ========== EXAMPLE USAGE ==========
 
  const CONTRACT_ADDRESS = '0x02D1B27260A8CE330aA2FDCCE3E8B7F7711A02A2C0776511fb5f42390f4216B6';
 
  // Example name to pass to say_hello function
  const name = 'Hello World';
 
  // Encode
  const base64CallData = encodeCallDataToBase64(CONTRACT_ADDRESS, name);
 
  // Initialize SDK
  const tachyon = new Tachyon({ apiKey: 'YOUR_API_KEY' });
 
  // Relay transaction
  const txId = await tachyon.relay({
    to: "0x02d1b27260a8ce330aa2fdcce3e8b7f7711a02a2c0776511fb5f42390f4216b6",
    callData: base64CallData,
    value: "0",
    chainId: 23448594291968334
  });
 
  console.log("Transaction ID:", txId);

Step-by-Step Instructions

Install the required dependencies:

terminal


  npm install @rathfi/tachyon ethers

Import the necessary modules:
- Import Tachyon and ChainId from @rathfi/tachyon
- Import ethers for encoding contract call data
Initialize the Tachyon SDK:
- Create a new Tachyon instance
- Pass your API key in the configuration object: { apiKey: 'YOUR_API_KEY' }
Define your contract ABI:
- Create an array with the function signature(s) you want to call
- Example: ["function sayHello(string message)"]
Encode the function call:
- Create an ethers Interface instance with your ABI
- Use encodeFunctionData() to encode the function name and parameters
- Store the result in callData
Submit the relay transaction:
- Call tachyon.relay() with the transaction parameters
- Use await since this is an asynchronous operation
Handle the transaction ID:
- The method returns a txId string
- Use this ID to track the transaction status through the Tachyon API

SDK Function Parameters

tachyon.relay(options)

Parameter	Type	Required	Description	Example
`chainId`	`ChainId` or `number`	Yes	Chain identifier (use ChainId enum or number)	`ChainId.BASE` or `8453`
`to`	`string`	Yes	Target contract address	`"0xA7A833e6641D7901F30EaD6f27d4Ee2C9bb670a7"`
`value`	`string`	Yes	Amount in wei	`"0"`
`callData`	`string`	Yes	Encoded function call data	Result from `iface.encodeFunctionData()`
`label`	`string`	Optional	Custom transaction label	`"Say Hello Example"`
`gasLimit`	`string`	Optional	Gas limit override	`"100000"`
`isAuthenticatedTx`	`boolean`	Optional	Authenticated relay mode	`true` or `false`
`transactionType`	`string`	Optional	Processing type	`"flash"` or `"flash-blocks"`

Returns: Promise<string> - The transaction ID (txId)

REST API

Using REST API

Code Example

terminal


curl -X POST https://api.tachyon.rath.fi/api/submit-tx \
  -H "apikey: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "0x02d1b27260a8ce330aa2fdcce3e8b7f7711a02a2c0776511fb5f42390f4216b6",
    "callData": "W3siY29udHJhY3RBZGRyZXNzIjoiMHgwMmQxYjI3MjYwYThjZTMzMGFhMmZkY2NlM2U4YjdmNzcxMWEwMmEyYzA3NzY1MTFmYjVmNDIzOTBmNDIxNmI2IiwiZW50cnlwb2ludCI6InNheV9oZWxsbyIsImNhbGxkYXRhIjpbIjAiLCIweDQxNmM2OTYzNjUiLCI1Il19XQ==",
    "value": "0",
    "chainId": 23448594291968334
  }'

Response:

response.json


{ "txId": "68fa3450539a3c9d28bbca33" }

Step-by-Step Instructions

Obtain your API key from the Tachyon dashboard at https://api.tachyon.rath.fi
Prepare your contract call data:
- Identify the target contract address (to)
- Encode your function call into callData (see SDK example for encoding details)
- Determine the chainId for your target network (e.g., 8453 for Base, 1 for Ethereum)
Set the transaction value:
- Use "0" for non-payable functions
- Specify the amount in wei as a string for payable functions
Make the API request:
- Send a POST request to https://api.tachyon.rath.fi/api/submit-tx
- Include your API key in the api-key header as YOUR_API_KEY
- Set Content-Type header to application/json
Handle the response:
- Extract the txId from the response
- Use this txId to track your transaction status

API Parameters

The RelayParams object defines the parameters required when calling the relay() method.

Name	Type	Required	Description
`chainId`	`number`	Yes	The blockchain network ID where the transaction will be executed. Must be a supported chain.
`to`	`string`	Yes	The recipient wallet address or smart contract address. Format varies by chain (hex for EVM, base58 for Solana, named for NEAR).
`callData`	`string`	Yes	Encoded transaction data in hexadecimal format (use ‘0x’ for simple transfers).
`value`	`string`	No	Amount of native currency to send in the smallest unit (wei for EVM, lamports for Solana, yoctoNEAR for NEAR). Defaults to ‘0’ if not specified.
`label`	`string`	No	Optional human-readable label for easier transaction identification and tracking.
`gasLimit`	`string`	No	Optional gas limit for the transaction. If not specified, it will be estimated automatically.
`gasPrice`	`string`	No	Gas price for legacy transactions. Cannot be used with `maxFeePerGas` or `maxPriorityFeePerGas`.
`maxFeePerGas`	`string`	No	Maximum fee per gas for EIP-1559 transactions. Must be used together with `maxPriorityFeePerGas`.
`maxPriorityFeePerGas`	`string`	No	Maximum priority fee per gas for EIP-1559 transactions. Must be used together with `maxFeePerGas`.
`maxUSD`	`number`	No	Maximum cost in USD that you’re willing to pay for this transaction.
`retries`	`number`	No	Number of retry attempts for the transaction. Defaults to 0.
`shouldBatchInMulticall`	`boolean`	No	Whether to batch this transaction in a multicall operation.
`isAuthenticatedTx`	`boolean`	No	Enable authenticated relay mode for additional security and verification. Defaults to false.
`derivationPath`	`string`	No	Optional HD wallet derivation path for transaction signing (useful for multi-account setups).
`transactionType`	`"flash" \| "authenticated" \| "funding-signed" \| "flash-blocks"`	No	Type of relay transaction. Defaults to `"flash"`. `"flash-blocks"` is only supported on Base (8453) and Base Sepolia (84532).
`authorizationList`	`AuthorizationListItem[]`	No	Optional list of authorization entries for delegated transactions or batched operations. Cannot be used with `"flash-blocks"` transaction type.

Transaction Lifecycle

After submitting your transaction through either the REST API or SDK:

Submission: The /api/submit-tx endpoint returns a unique txId
Queued: Transaction enters the relay queue with NOT_PICKED_UP status
Processing: A relay node picks up and broadcasts the transaction to the blockchain
Executed: Transaction gets confirmed on-chain; execution hash becomes available

You can use the txId to query the transaction status and retrieve the execution hash once confirmed.

Summary

The Tachyon Relay API provides a simple, unified interface for interacting with smart contracts across multiple blockchain networks. Whether you’re using the REST API for direct HTTP calls or the TypeScript SDK for type-safe integration, the process remains straightforward: encode your contract call, submit it to the relay, and track it using the returned transaction ID.