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Sign a Transaction

Prerequisites

Before you can sign a transaction, you need:

A valid FSCO API key
A wallet ID for the wallet you want to use for signing
The transaction data to sign in hex format

Endpoint

POST /v2/wallet/{walletId}/sign/tx

Parameters

Parameter	Type	Required	Description
`walletId`	string	Yes	The unique ID of the wallet to use for signing
`data`	string	Yes	The transaction data to be signed in hex format (must start with ‘0x’)

Examples

#!/bin/bash

curl -X POST "https://api.fsco.io/v2/wallet/8c1d496f-2827-4750-a11f-74b48c11108d/sign/tx" \
  -H "Authorization: Bearer ${FSCO_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "walletId": "8c1d496f-2827-4750-a11f-74b48c11108d",
    "data": "0x02f87082000189059682f00085059682f10825208947..."
  }'

import axios from 'axios';

const FSCO_API_KEY = process.env.FSCO_API_KEY;
const FSCO_API_SECRET = process.env.FSCO_API_SECRET;
const walletId = '8c1d496f-2827-4750-a11f-74b48c11108d';

async function signTransaction() {
  try {
    const response = await axios.post(
      `https://api.fsco.io/v2/wallet/${walletId}/sign/tx`,
      {
        walletId,
        data: '0x02f87082000189059682f00085059682f10825208947...'
      },
      {
        headers: {
          'Content-Type': 'application/json',
          'x-api-key': FSCO_API_KEY,
          'x-api-secret': FSCO_API_SECRET
        }
      }
    );

    console.log('Signed transaction:', response.data);
    return response.data;
  } catch (error) {
    console.error('Error signing transaction:', error);
    throw error;
  }
}

signTransaction();

import os
import requests

FSCO_API_KEY = os.environ.get("FSCO_API_KEY")
FSCO_API_SECRET = os.environ.get("FSCO_API_SECRET")
wallet_id = "8c1d496f-2827-4750-a11f-74b48c11108d"


def sign_transaction():
    try:
        response = requests.post(
            f"https://api.fsco.io/v2/wallet/{wallet_id}/sign/tx",
            json={
                "walletId": wallet_id,
                "data": "0x02f87082000189059682f00085059682f10825208947...",
            },
            headers={
                "Content-Type": "application/json",
                "x-api-key": FSCO_API_KEY,
                "x-api-secret": FSCO_API_SECRET
            },
        )
        response.raise_for_status()
        print("Signed transaction:", response.json())
        return response.json()
    except requests.exceptions.RequestException as e:
        print("Error signing transaction:", e)
        raise


if __name__ == "__main__":
    sign_transaction()

using System;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program
{
    static readonly string FSCO_API_KEY = Environment.GetEnvironmentVariable("FSCO_API_KEY");
    static readonly string walletId = "8c1d496f-2827-4750-a11f-74b48c11108d";

    static async Task Main()
    {
        await SignTransaction();
    }

    static async Task SignTransaction()
    {
        try
        {
            using var client = new HttpClient();
            client.DefaultRequestHeaders.Add("Authorization", $"Bearer {FSCO_API_KEY}");

            var request = new
            {
                walletId = walletId,
                data = "0x02f87082000189059682f00085059682f10825208947..."
            };

            var content = new StringContent(
                JsonSerializer.Serialize(request),
                Encoding.UTF8,
                "application/json"
            );

            var response = await client.PostAsync(
                $"https://api.fsco.io/v2/wallet/{walletId}/sign/tx",
                content
            );

            response.EnsureSuccessStatusCode();
            var result = await response.Content.ReadAsStringAsync();
            Console.WriteLine($"Signed transaction: {result}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error signing transaction: {ex.Message}");
            throw;
        }
    }
}

Response

JSON

{
  "walletId": "8c1d496f-2827-4750-a11f-74b48c11108d",
  "signedData": "0x02f87082000189059682f00085059682f10825208947..."
}

The response includes:

walletId: The ID of the wallet that signed the transaction
signedData: The signed transaction data in hex format

Notes

The transaction data must be in hex format and start with ‘0x’
The wallet must exist and be active
The signed transaction is automatically broadcast to the network
The walletId in the path must match the walletId in the request body

Next Steps