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.)

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.

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)

Aptos

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": 88888888,
      "to": "0x3690a8173c5f738234d3772621db2923cf283029d0b9a7795038fde6f3fcdabd",
      "value": "0",
      "callData": "eyJmdW5jdGlvbiI6IjB4MzY5MGE4MTczYzVmNzM4MjM0ZDM3NzI2MjFkYjI5MjNjZjI4MzAyOWQwYjlhNzc5NTAzOGZkZTZmM2ZjZGFiZDo6aGVsbG9fdGFjaHlvbl92Mjo6cHJldmlld19tZXNzYWdlIiwidHlwZUFyZ3VtZW50cyI6W10sImZ1bmN0aW9uQXJndW1lbnRzIjpbIkdNIFRhY2h5b24hIl19",
      "label": "send-to-aptos",
      "gasLimit": "5000"
    }'

Response:

response.json


{ "txId": "68fa3450539a3c9d28bbca33" }

callData Structure (before Base64 encoding)

aptos-payload.json


{
  "function": "0x3690a8173c5f738234d3772621db2923cf283029d0b9a7795038fde6f3fcdabd::hello_tachyon_v2::preview_message",
  "typeArguments": [],
  "functionArguments": ["GM Tachyon!"]
}

Solana

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": "MemoSq4gqABAXKb96qnH8TysNcWxMyWCqXgDLGmfcHr",
    "callData": "eyJwcm9ncmFtSWQiOiJNZW1vU3E0Z3FBQkFYS2I5NnFuSDhUeXNOY1d4TXlXQ3FYZ0RMR21mY0hyIiwia2V5cyI6W10sImRhdGEiOiJTR1ZzYkc4Z1puSnZiU0J5WVhSbyJ9",
    "value": "0",
    "chainId": 10100000,
    "label": "call-contract-solana"
  }'

Step-by-Step Instructions

Example integration for Solana will be added soon.
Developers will be able to relay compiled BPF contract calls using the same /api/submit-tx endpoint.

API Parameters

Documentation will be available soon with Solana-specific parameter details.

Sui

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

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": 7777777,
    "to": "rathgreeting.near",
    "value": "0",
    "callData": "eyJtZXRob2ROYW1lIjoic2V0X2dyZWV0aW5nIiwiYXJncyI6eyJncmVldGluZyI6IkhlbGxvIGZyb20gdGFjaHlvbiEifX0=",
    "label": "contract-call-near"
  }'

Response:

response.json


{ "txId": "68fa3450539a3c9d28bbca33" }

callData Structure (before Base64 encoding)

near-method-call.json


{
  "methodName": "set_greeting",
  "args": {
    "greeting": "Hello from tachyon!"
  }
}

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.