> For the complete documentation index, see [llms.txt](https://docs-sdk.crypto-chief.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-sdk.crypto-chief.com/processing/js/guides/contract-calls.md).

# Contract calls (EVM / TRON)

Call EVM, TRON, and Solana contracts in Node.js without hand-encoding calldata.

Most real-world transactions are smart-contract calls. You never encode the `data` field by hand: give the SDK a typed description and get back a signed reservation.

{% hint style="warning" %}
Contract-type transactions (`signEvmCall`, `erc20Transfer`, `signTronCall`, `signAnchorCall` — every helper in this guide signs `type=contract`) are covered by the same [execute-time pre-flight](/processing/js/guides/sign-execute.md): a wallet without enough native coin for gas gets `PREFLIGHT_FAILED` instead of an on-chain revert or a silent gas burn. On TRON, the call is additionally simulated, so a reverting call (including an insufficient token balance) is rejected as `simulation_reverted` before any fee is spent.
{% endhint %}

## EVM — by Solidity signature

{% hint style="danger" %}
This snippet shows the **encoder**, not a complete swap. Two things have to be true before a swap like this succeeds on chain:

* **An allowance.** Uniswap's router moves your input token with `transferFrom`, so it needs an ERC-20 `approve(address,uint256)` on that token first, confirmed before the swap is signed — the nonce comes from chain state. Without it the swap reverts and burns the gas.
* **A slippage floor.** `amountOutMin` of `0` accepts whatever the pool returns, which on a public mempool hands the trade to the first sandwich bot that sees it. Pass a real minimum, in the output token's base units.
  {% endhint %}

```ts
import { humanToBase } from '@cryptochiefs/cryptochief-crypto-processing-node';

const amountIn = humanToBase('0.01', 18);
const deadline = BigInt(Math.floor(Date.now() / 1000) + 600);

const signed = await client.transactions.signEvmCall({
  network: Chain.EthMainnet,
  fromAddress: '0xYourWallet...',
  contract: '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D', // Uniswap V2 router
  method: 'swapExactTokensForTokens(uint256,uint256,address[],address,uint256)',
  args: [amountIn, 0n, [tokenIn, tokenOut], '0xYou...', deadline],
  urlCallback: 'https://your.app/webhooks/transaction',
});
```

The encoder supports `uint/int<M>`, `address`, `bool`, `bytes`, `bytes<N>`, `string`, and fixed/dynamic arrays of those. Argument values accept `bigint`, integer `number`, decimal/hex strings, `Uint8Array`, and arrays.

## ERC-20 / TRC-20 transfer (one-liner)

```ts
const amount = humanToBase('12.5', 6); // USDT has 6 decimals

await client.transactions.erc20Transfer({
  network: Chain.EthMainnet,
  fromAddress: '0xYourWallet...',
  tokenContract: '0xdAC17F958D2ee523a2206206994597C13D831ec7',
  recipient: '0xRecipient...',
  amount,
});
```

## TRON — same encoder, base58 addresses

`signTronCall` (an alias of `signEvmCall`) accepts both base58 (`T...`) and `0x41`-prefixed hex addresses:

```ts
await client.transactions.signTronCall({
  network: Chain.TronMainnet,
  fromAddress: 'TYourWallet...',
  contract: 'TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t', // USDT TRC-20
  method: 'transfer(address,uint256)',
  args: ['TRecipient...', amount],
});
```

## Solana — Anchor program

```ts
import { borshU64, borshString } from '@cryptochiefs/cryptochief-crypto-processing-node';

const signed = await client.transactions.signAnchorCall({
  network: Chain.SolanaMainnet,
  fromAddress: 'YourWallet...',
  program: 'YourProgramId...',
  method: 'initialize',
  args: [borshU64(1_000_000n), borshString('hello')],
  accounts: [
    { pubkey: 'YourWallet...', isSigner: true, isWritable: true },
  ],
});
```

For TON contracts, see [TON transfers](/processing/js/guides/ton.md).