Binance API place order

Question

How do I place an order for futures? I am getting two errors: "The required timestamp parameter was not sent, was empty / null, or is not well formed." OR "The signature for this request is not valid."

public static async void Order()
    {
        string base_uri = "https://fapi.binance.com/fapi/v1/order?";
        string API_Key = "bSQQlu2k5tf0oSUGZsNGptisIxXLux8wb............................";
        string Secret_Key = "gWPKP66geFL0ryijnlU3TTepS61.............................";

        string symbol = "XRPUSDT";
        string side = "BUY";
        string type = "MARKET";
        string timeInForce = "GTC";

        decimal quantity = 20;
        long recvWindow = 5000;
        long timestamp = GetServerTime();

        string queryString = "symbol=" + symbol + "&side=" + side + "type=" + type + "&timeInForce=" + timeInForce;
        string signature = HMACHASH(queryString, Secret_Key);

        var Payload = new Credentials
        {
            Quantity = quantity,
            RecvWindow = recvWindow,
            Timestamp = timestamp,
            Signature = signature
        };

        var stringPayload = JsonConvert.SerializeObject(Payload);
        var httpContent = new StringContent(stringPayload, Encoding.UTF8, "application/json");

        httpContent.Headers.Add("X-MBX-APIKEY", API_Key);

        using (var httpClient = new HttpClient())
        {

            var httpResponse = await httpClient.PostAsync(base_uri + queryString, httpContent);
            if (httpResponse.Content != null)
            {
                var responseContent = await httpResponse.Content.ReadAsStringAsync();
                Console.WriteLine(responseContent);
            }
        }

    }

This is how I get the timestamp

public static long GetServerTime()
    {
        string str = BinanceResponse("https://fapi.binance.com/fapi/v1/time");
        string[] arr = str.Split('\"');
        str = arr[2].Trim(':', '}');
        return long.Parse(str);
    }

Credentials class

internal class Credentials
{
    [JsonProperty("quantity")]
    public decimal Quantity { get; set; }
    [JsonProperty("recvWindow")]
    public long RecvWindow { get; set; }
    [JsonProperty("timestamp")]
    public long Timestamp { get; set; }
    [JsonProperty("signature")]
    public string Signature { get; set; }
}

After serialization

stringPayload = "{"quantity":20.0,"recvWindow":5000,"timestamp":1625061703897,"signature":"2794e66d4e5b5b6338782e058747a567db523.........................."}"

If I try like this:

string queryString = "symbol=" + symbol + "&side=" + side + "&type=" + type + 
            "&timeInForce=" + timeInForce + "&quantity=" + quantity + "&recvWindow=" + 
            recvWindow + "&timestamp=" + timestamp;

string signature = HMACHASH(queryString, Secret_Key);
queryString += "&signature=" + signature;

Error: "The signature for this request is not valid."

Resolved! Thank you guys! I used Fiddler and found out that the "timeInForce" parameter is not needed for a type = "MARKET". All the problems were because of him.

string queryString = "symbol=" + symbol + "&side=" + side + "&type=" + type + 
             ̶"̶&̶t̶i̶m̶e̶I̶n̶F̶o̶r̶c̶e̶=̶"̶ ̶+̶ ̶t̶i̶m̶e̶I̶n̶F̶o̶r̶c̶e̶  + "&quantity=" + quantity + "&recvWindow=" + 
            recvWindow + "&timestamp=" + timestamp;

Answer 1

The response is in the error report. The Binance API require you to send an timestamp.

So you are probably not sending a correct timestamp or not correctly name it.

You can check your requests with an http sniffer like Fiddler.

It's possible that the API is case sensitive so, timestamp should not be "Timestamp" after the serialization. Check it

EDIT: Can you provide the documentation that you used to create the request ? Because the official binance API is asking for POST parameters only