> 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/go/guides/contract-calls.md).

# Contract calls (EVM / TRON)

Call EVM, TRON, and Solana contracts in Go 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/go/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 %}

```go
amountIn, _ := cryptochief.HumanToBase("0.01", 18)

signed, _ := c.Transactions.SignEVMCall(ctx, &cryptochief.EVMCallRequest{
    Network:     cryptochief.ChainEthMainnet,
    FromAddress: "0xYourWallet...",
    Contract:    "0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D", // Uniswap V2 router
    Method:      "swapExactTokensForTokens(uint256,uint256,address[],address,uint256)",
    Args:        []any{amountIn, big.NewInt(0), []string{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 `*big.Int`, plain Go ints, decimal/hex strings, `[]byte`, and slices.

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

```go
amount, _ := cryptochief.HumanToBase("12.5", 6) // USDT has 6 decimals

c.Transactions.ERC20Transfer(ctx, &cryptochief.ERC20TransferRequest{
    Network:       cryptochief.ChainEthMainnet,
    FromAddress:   "0xYourWallet...",
    TokenContract: "0xdAC17F958D2ee523a2206206994597C13D831ec7",
    Recipient:     "0xRecipient...",
    Amount:        amount,
})
```

## TRON — same encoder, base58 addresses

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

```go
c.Transactions.SignTronCall(ctx, &cryptochief.EVMCallRequest{
    Network:     cryptochief.ChainTronMainnet,
    FromAddress: "TYourWallet...",
    Contract:    "TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t", // USDT TRC-20
    Method:      "transfer(address,uint256)",
    Args:        []any{"TRecipient...", amount},
})
```

## Solana — Anchor program

```go
signed, _ := c.Transactions.SignAnchorCall(ctx, &cryptochief.AnchorCallRequest{
    Network:     cryptochief.ChainSolanaMainnet,
    FromAddress: "YourWallet...",
    Program:     "YourProgramId...",
    Method:      "initialize",
    Args: []cryptochief.BorshValue{
        cryptochief.BorshU64(1_000_000),
        cryptochief.BorshString("hello"),
    },
    Accounts: []cryptochief.SolanaAccount{
        {Pubkey: "YourWallet...", IsSigner: true, IsWritable: true},
    },
})
```

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