Using Litjson
void Start () { // Use litJson to create parameter data in json format JsonData data = new JsonData (); data [ " Parameter name negotiated with backend " ] = " Parameter you want to write " ; byte [] postBytes = System.Text.Encoding.Default.GetBytes (data.ToJson ()); // use native UnityWebRequest (recommended) StartCoroutine (UnityWebRequestPost ( " your url " , postBytes)); // use UniRx ObservableWWW.Post ( " you Url " , postBytes, new Dictionary < string, string>() { { "Content-Type", "application/json" } }) .Subscribe(result => Debug.Log(result)); } IEnumerator UnityWebRequestPost(string url, byte[] postBytes) { UnityWebRequest request = new UnityWebRequest(url, "POST"); request.uploadHandler = (UploadHandler)new UploadHandlerRaw(postBytes); request.downloadHandler = (DownloadHandler)new DownloadHandlerBuffer(); request.SetRequestHeader("Content-Type", "application/json"); yield return request.SendWebRequest(); Debug.Log("Status Code: " + request.responseCode); if (request.isNetworkError || request.isHttpError) { Debug.LogError(request.error); } else { Debug.Log(request.downloadHandler.text); } }