---
title: sign
---
# sign <TitleWithCodeLink2 link="sign" />
Sign a provided transaction object or a hex formatted string

>
> **! WARNING** 
>
> Do not use this in any web / user-facing applications. This will expose the private key.
> 
> Signing a hex-formatted string with this API is discouraged and will be deprecated in a future release. Please use [signMessageV2](./signMessageV2.md) for message signing.

## Usage
```js
// sign a transaction
tronWeb.trx.sign(transaction, privateKey);

// or
// sign a Hex formatted string
tronWeb.trx.sign(str, privateKey)
```

## Parameters
| Parameters                         | Parameter Description                                                                                                        | Data Type     |
|------------------------------------|------------------------------------------------------------------------------------------------------------------------------|---------------|
| transaction / Hex formatted string | The transaction object / hex formatted string                                                                                | JSON / String |
| privateKey                         | The private key used for signing. Optional. The default value is the private key passed in when constructing tronweb object. | String        |

## Return
Object - The signed transaction object.
or
String - The signature hex string.

## Example
```js
const tradeobj = await tronWeb.transactionBuilder.sendTrx("TNo9e8MWQpGVqdyySxLSTw3gjgFQWE3vfg", 100,"TM2TmqauSEiRf16CyFgzHV2BVxBejY9iyR");  
const signedtxn = await tronWeb.trx.sign(tradeobj, privateKey);
console.log(signedtxn)
// output-start
{
  visible: false,
  txID:
   'cbf76171dcf5f8fe00b4911a1a6cc4d2a4448e3348f44d240ca20af06025d0f2',
  raw_data:
   { contract: [ [Object] ],
     ref_block_bytes: '6394',
     ref_block_hash: '8ad966a9b0b6a5d1',
     expiration: 1580983512000,
     timestamp: 1580983453441 },
  raw_data_hex:
   '0a02639422088ad966a9b0b6a5d140c0d7d7cf812e5a65080112610a2d747970652e676f6f676c65617069732e636f6d2f70726f746f636f6c2e5472616e73666572436f6e747261637412300a15417946f66d0fc67924da0ac9936183ab3b07c811261215418cb2ab880d4fa7b33c9645a2276dc9b192902e2d186470818ed4cf812e',
  signature:
   [ '47b1f77b3e30cfbbfa41d795dd34475865240617dd1c5a7bad526f5fd89e52cd057c80b665cc2431efab53520e2b1b92a0425033baee915df858ca1c588b0a1800' ] }
// output-end
```