Hi Sara,
I would appreciate your comments about this issue
Background: 
   1-  In page 66 Build_Web_Servers_ESP32_ESP8266_V2.pdf you suggest installing   Arduino_JSON
 
   2- In tutorial  https://randomnerdtutorials.com/esp32-http-get-post-arduino/
       you wrote  “You also need to install the Arduino_JSON library”
 
 But later in the same tutorial (https://randomnerdtutorials.com/esp32-http-get-post-arduino/)  
the code for json request is 
// If you need an HTTP request with a content type: application/json, use the following:
//http.addHeader(“Content-Type”, “application/json”);
//int httpResponseCode = http.POST(“{\”api_key\”:\”tPmAT5Ab3j7F9\”,\”sensor\”:\”BME280\”,\”value1\”:\”24.25\”,\”value2\”:\”49.54\”,\”value3\”:\”1005.14\”}”); 
Code that I do not found user friendly.
 
Looking for alternatives I found this code 
// Prepare JSON document
DynamicJsonDocument doc(2048);
doc[“hello”] = “world”;
// Serialize JSON document
String json;
serializeJson(doc, json);
WiFiClient client; // or WiFiClientSecure for HTTPS
HTTPClient http;
// Send request
http.begin(client, “http://httpbin.org/post”);
http.POST(json);
 
But it seems that this code does not work Arduino_JSON
 
My questions:
1- What is your opinion about replacing Arduino_JSON with ArduinoJson.
2- Are there any licensing issues?
3- How to implement a more friendly code for a POST request with json and Arduino_JSON library
 
Thanks in advance for your help