> ## Documentation Index
> Fetch the complete documentation index at: https://docs-en.keysecure.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Web3 Transaction Callback

**Co-Signer** calls back to the client system to confirm whether the web3 transaction is normal before signing.

`Content-Type application/json;charset=UTF-8`

#### Callback Request Parameters

| Param | Type | Required | Description |
| :- | :- | :- | :- |
| type | String | Yes | Callback type: `sign_prepare`prepare to sign，`sign_start` for signature initiation, `sign_success` for successful signature |
| trans\_id | Integer | Yes | Transaction ID |
| request\_id | String | Yes | Unique identifier for the transaction |
| pending\_round | Boolean | Yes | Acceleration status: `true` for accelerated transactions, `false` for regular transactions |
| from | String | Yes | Sender address of the transaction |
| to | String | Yes | Recipient address of the transaction |
| amount | Decimal | Yes | Transaction amount. Use `-1` for infinity |
| main\_chain\_symbol | String | Yes | Network symbol (unique identifier), e.g., "ETH" |
| input\_data | String | Yes | Input data for the transaction |
| interactive\_contract | String | Yes | Interactive contract |
| txid | String | No | Transaction hash. Returned when the signature is successful |

```curl cURL theme={null}
curl -X POST \
--url 'https://custom-url/example-callback' \
--data '{
      "type":"sign_start",
      "trans_id":432,
      "request_id":"0000000003",
      "pending_round":false,
      "from":"0xc70d1eebb7c687ec8d56bead73f104d41e6e0bda",
      "to":"0x5EDc9177997Bf6B4db559A5C184051858B3B3704",
      "amount":0,
      "main_chain_symbol":"HECO",
      "input_data":"0xca718c65",
      "interactive_contract":"0xe012F3957226894B1a2a44b3ef5070417a069dC2",
      "txid":"",
}'
```

#### Callback Response Parameters

Return string：

* `SUCCESS` means SUCCESS: Co-Signer signs the transaction.
* `FAILURE` means FAILURE: Co-Signer will ignore the transaction and not sign.


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.