ESP32 HTTP GET and HTTP POST with Arduino IDE (JSON, URL Encoded, Text)

In this guide, you’ll learn how to make HTTP GET and HTTP POST requests with the ESP32 board with Arduino IDE. We’ll cover examples on how to get values, post JSON objects, URL encoded requests, and more.

ESP32 HTTP GET and HTTP POST with Arduino IDE (JSON, URL Encoded, Text)

Recommended: ESP8266 NodeMCU HTTP GET and HTTP POST with Arduino IDE (JSON, URL Encoded, Text)

HTTP Request Methods: GET vs POST

The Hypertext Transfer Protocol (HTTP) works as a request-response protocol between a client and server. Here’s an example:

  • The ESP32 (client) submits an HTTP request to a Raspberry Pi running Node-RED (server);
  • The server returns a response to the ESP32 (client);
  • Finally, the response contains status information about the request and may also contain the requested content.

HTTP GET

GET is used to request data from a specified resource. It is often used to get values from APIs.

For example, you can have:

GET /update-sensor?temperature=value1

Note that the query string (name = temperature and value = value1) is sent in the URL of the HTTP GET request.

Or you can use a simple request to return a value or JSON object, for example:

GET /get-sensor

(With HTTP GET, data is visible to everyone in the URL request.)

HTTP POST

POST is used to send data to a server to create/update a resource. For example, publish sensor readings to a server.

The data sent to the server with POST is stored in the request body of the HTTP request:

POST /update-sensor HTTP/1.1
Host: example.com
api_key=api&sensor_name=name&temperature=value1&humidity=value2&pressure=value3
Content-Type: application/x-www-form-urlencoded

In the body request, you can also send a JSON object:

POST /update-sensor HTTP/1.1
Host: example.com
{api_key: "api", sensor_name: "name", temperature: value1, humidity: value2, pressure: value3}
Content-Type: application/json

(With HTTP POST, data is not visible in the URL request. However, if it’s not encrypted, it’s still visible in the request body.)

HTTP GET/POST with ESP32

In this guide, we’ll explore the following scenarios:

  1. ESP32 HTTP GET: Value or Query in URL
  2. ESP32 HTTP GET: JSON Data Object or Plain Text
  3. ESP32 HTTP POST: URL Encoded, JSON Data Object, Plain Text

Prerequisites

Before proceeding with this tutorial, make sure you complete the following prerequisites.

Arduino IDE

We’ll program the ESP32 using Arduino IDE, so make sure you have the ESP32 add-on installed.

Arduino_JSON Library

You also need to install the Arduino_JSON library. You can install this library in the Arduino IDE Library Manager. Just go to Sketch Include Library > Manage Libraries and search for the library name as follows:

Install Arduino JSON library Arduino IDE

Parts Required

For this tutorial you need the following parts:

You can use the preceding links or go directly to MakerAdvisor.com/tools to find all the parts for your projects at the best price!

Preparing Node-RED (optional)

As an example, we’ll create a web service with a Raspberry Pi and Node-RED to act as a web service (like an API). Basically, you’ll make HTTP GET and HTTP POST requests to your Raspberry Pi to get values or update them. You can use any other web service.

If you don’t have Node-RED installed, follow the next tutorials:

Having Node-RED running on your Raspberry Pi, go to your Raspberry Pi IP address followed by :1880.

http://raspberry-pi-ip-address:1880

The Node-RED interface should open. You can simply import the final flow:

Node-RED-Flow-HTTP-GET-POST-Request-Methods-ESP32-ESP8266-Arduino

Go to Menu > Import and copy the following to your Clipboard to create your Node-RED flow.

[{"id":"599740b7.efde9","type":"http response","z":"b01416d3.f69f38","name":"","statusCode":"200","headers":{},"x":420,"y":689,"wires":[]},{"id":"1618a829.76f638","type":"json","z":"b01416d3.f69f38","name":"","property":"payload","action":"obj","pretty":true,"x":410,"y":809,"wires":[["d0089cc7.d25ac"]]},{"id":"c7410fa2.1c2fa","type":"debug","z":"b01416d3.f69f38","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":850,"y":709,"wires":[]},{"id":"75a22f74.f1aba","type":"ui_text","z":"b01416d3.f69f38","group":"2b7ac01b.fc984","order":1,"width":0,"height":0,"name":"","label":"Sensor Name","format":"{{msg.payload}}","layout":"row-spread","x":860,"y":769,"wires":[]},{"id":"1c8f9093.8bc2bf","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"2b7ac01b.fc984","order":2,"width":0,"height":0,"gtype":"gage","title":"Temperature","label":"ºC","format":"{{value}}","min":0,"max":"38","colors":["#00b500","#e6e600","#ca3838"],"seg1":"","seg2":"","x":850,"y":829,"wires":[]},{"id":"a5bd2706.54e108","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"2b7ac01b.fc984","order":3,"width":0,"height":0,"gtype":"gage","title":"Humidity","label":"%","format":"{{value}}","min":0,"max":"100","colors":["#0080ff","#0062c4","#002f5e"],"seg1":"","seg2":"","x":840,"y":889,"wires":[]},{"id":"105ac2cc.7b3cfd","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"2b7ac01b.fc984","order":4,"width":0,"height":0,"gtype":"gage","title":"Pressure","label":"hPa","format":"{{value}}","min":0,"max":"1200","colors":["#b366ff","#8000ff","#440088"],"seg1":"","seg2":"","x":840,"y":949,"wires":[]},{"id":"d0089cc7.d25ac","type":"function","z":"b01416d3.f69f38","name":"JSON or URL Encoded","func":"var msg0 = { payload: msg.payload.api_key };\nvar msg1 = { payload: msg.payload.sensor };\nvar msg2 = { payload: msg.payload.value1 };\nvar msg3 = { payload: msg.payload.value2 };\nvar msg4 = { payload: msg.payload.value3 };\n\nreturn [msg0, msg1, msg2, msg3, msg4];","outputs":5,"noerr":0,"x":610,"y":809,"wires":[["c7410fa2.1c2fa"],["75a22f74.f1aba"],["1c8f9093.8bc2bf"],["a5bd2706.54e108"],["105ac2cc.7b3cfd"]]},{"id":"5d9ab0d2.66b92","type":"http in","z":"b01416d3.f69f38","name":"","url":"update-sensor","method":"post","upload":false,"swaggerDoc":"","x":200,"y":740,"wires":[["599740b7.efde9","c7410fa2.1c2fa","1618a829.76f638"]]},{"id":"7f5cf345.63f56c","type":"http response","z":"b01416d3.f69f38","name":"","statusCode":"200","headers":{},"x":540,"y":420,"wires":[]},{"id":"6530621.95b429c","type":"http in","z":"b01416d3.f69f38","name":"","url":"/get-sensor","method":"get","upload":false,"swaggerDoc":"","x":180,"y":600,"wires":[["9471d1a0.68588"]]},{"id":"5ddc9f47.4b555","type":"http response","z":"b01416d3.f69f38","name":"","statusCode":"200","headers":{},"x":540,"y":560,"wires":[]},{"id":"9471d1a0.68588","type":"function","z":"b01416d3.f69f38","name":"","func":"msg.payload = {\"value1\":24.25, \"value2\":49.54, \"value3\":1005.14};\nreturn msg;","outputs":1,"noerr":0,"x":350,"y":600,"wires":[["5ddc9f47.4b555","13aea59.7430e5a"]]},{"id":"13aea59.7430e5a","type":"debug","z":"b01416d3.f69f38","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":550,"y":628,"wires":[]},{"id":"e71c7a7d.e7c598","type":"debug","z":"b01416d3.f69f38","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":550,"y":500,"wires":[]},{"id":"c7807102.3f433","type":"http in","z":"b01416d3.f69f38","name":"","url":"/update-sensor","method":"get","upload":false,"swaggerDoc":"","x":190,"y":460,"wires":[["60410cde.562a34"]]},{"id":"60410cde.562a34","type":"function","z":"b01416d3.f69f38","name":"","func":"msg.payload = msg.payload.temperature;\nreturn msg;","outputs":1,"noerr":0,"x":390,"y":460,"wires":[["e71c7a7d.e7c598","7f5cf345.63f56c"]]},{"id":"2b7ac01b.fc984","type":"ui_group","z":"","name":"SENSORS","tab":"99ab8dc5.f435c","disp":true,"width":"6","collapse":false},{"id":"99ab8dc5.f435c","type":"ui_tab","z":"","name":"HTTP","icon":"dashboard","order":1,"disabled":false,"hidden":false}]

View raw code

Other Web Services or APIs

In this guide, the ESP32 performs HTTP requests to Node-RED, but you can use these examples with other services like ThingSpeak, IFTTT.com (Web Hooks service), OpenWeatherMap.org, PHP server, etc… All examples presented in this guide will also work with other APIs.

In summary, to make this guide compatible with any service, you need to search for the service API documentation. Then, you need the server name (URL or IP address), and parameters to send in the request (URL path or request body). Finally, modify our examples to integrate with any API you want to use.

1. ESP32 HTTP GET: Value or Query in URL

In the first example, the ESP32 will make an HTTP GET request to update a reading in a service. This type of request could also be used to filter a value, request a value or return a JSON object.

HTTP GET ESP32 Get Sensor Value Plain Text Status 200 OK

Code ESP32 HTTP GET with Arduino IDE

After installing the necessary board add-ons and libraries, copy the following code to your Arduino IDE, but don’t upload it yet. You need to make some changes to make it work for you.

/*
  Rui Santos
  Complete project details at Complete project details at https://RandomNerdTutorials.com/esp32-http-get-post-arduino/

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files.

  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
*/

#include <WiFi.h>
#include <HTTPClient.h>

const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";

//Your Domain name with URL path or IP address with path
String serverName = "http://192.168.1.106:1880/update-sensor";

// the following variables are unsigned longs because the time, measured in
// milliseconds, will quickly become a bigger number than can be stored in an int.
unsigned long lastTime = 0;
// Timer set to 10 minutes (600000)
//unsigned long timerDelay = 600000;
// Set timer to 5 seconds (5000)
unsigned long timerDelay = 5000;

void setup() {
  Serial.begin(115200); 

  WiFi.begin(ssid, password);
  Serial.println("Connecting");
  while(WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to WiFi network with IP Address: ");
  Serial.println(WiFi.localIP());
 
  Serial.println("Timer set to 5 seconds (timerDelay variable), it will take 5 seconds before publishing the first reading.");
}

void loop() {
  //Send an HTTP POST request every 10 minutes
  if ((millis() - lastTime) > timerDelay) {
    //Check WiFi connection status
    if(WiFi.status()== WL_CONNECTED){
      HTTPClient http;

      String serverPath = serverName + "?temperature=24.37";
      
      // Your Domain name with URL path or IP address with path
      http.begin(serverPath.c_str());
      
      // Send HTTP GET request
      int httpResponseCode = http.GET();
      
      if (httpResponseCode>0) {
        Serial.print("HTTP Response code: ");
        Serial.println(httpResponseCode);
        String payload = http.getString();
        Serial.println(payload);
      }
      else {
        Serial.print("Error code: ");
        Serial.println(httpResponseCode);
      }
      // Free resources
      http.end();
    }
    else {
      Serial.println("WiFi Disconnected");
    }
    lastTime = millis();
  }
}

View raw code

Setting your network credentials

Modify the next lines with your network credentials: SSID and password. The code is well commented on where you should make the changes.

// Replace with your network credentials
const char* ssid     = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";

Setting your serverName

You also need to type your domain name or Node-RED IP address, so the ESP publishes the readings to your own server.

String serverName = "http://192.168.1.106:1880/update-sensor";

Now, upload the code to your board and it should work straight away.

Read the next section, if you want to learn how to make the HTTP GET request.

HTTP GET Request

In the loop() is where you actually make the HTTP GET request every 5 seconds with sample data:

String serverPath = serverName + "?temperature=24.37";

// Your Domain name with URL path or IP address with path
http.begin(serverPath.c_str());

// Send HTTP GET request
int httpResponseCode = http.GET();

The ESP32 makes a new request in the following URL to update the sensor field with a new temperature.

http://192.168.1.106:1880/update-sensor?temperature=24.37

Then, the following lines of code save the HTTP response from the server.

if (httpResponseCode>0) {
  Serial.print("HTTP Response code: ");
  Serial.println(httpResponseCode);
  String payload = http.getString();
  Serial.println(payload);
}
else {
  Serial.print("Error code: ");
  Serial.println(httpResponseCode);
}

Demonstration

With your board running the new sketch, open the Node-RED debug window. You’ll see that the sample values are being printed successfully (24.37).

2. ESP32 HTTP GET: JSON Data Object or Plain Text

This next example shows how to make an HTTP GET request to get a JSON object and decode it with the ESP32. Many APIs return data in JSON format.

HTTP GET ESP32 Get Sensor JSON Data

Copy the next sketch to your Arduino IDE (type your SSID and password):

/*
  Rui Santos
  Complete project details at Complete project details at https://RandomNerdTutorials.com/esp32-http-get-post-arduino/

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files.

  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
*/

#include <WiFi.h>
#include <HTTPClient.h>
#include <Arduino_JSON.h>

const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";

//Your Domain name with URL path or IP address with path
const char* serverName = "http://192.168.1.106:1880/get-sensor";

// the following variables are unsigned longs because the time, measured in
// milliseconds, will quickly become a bigger number than can be stored in an int.
unsigned long lastTime = 0;
// Timer set to 10 minutes (600000)
//unsigned long timerDelay = 600000;
// Set timer to 5 seconds (5000)
unsigned long timerDelay = 5000;

String sensorReadings;
float sensorReadingsArr[3];

void setup() {
  Serial.begin(115200);

  WiFi.begin(ssid, password);
  Serial.println("Connecting");
  while(WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to WiFi network with IP Address: ");
  Serial.println(WiFi.localIP());
 
  Serial.println("Timer set to 5 seconds (timerDelay variable), it will take 5 seconds before publishing the first reading.");
}

void loop() {
  //Send an HTTP POST request every 10 minutes
  if ((millis() - lastTime) > timerDelay) {
    //Check WiFi connection status
    if(WiFi.status()== WL_CONNECTED){
              
      sensorReadings = httpGETRequest(serverName);
      Serial.println(sensorReadings);
      JSONVar myObject = JSON.parse(sensorReadings);
  
      // JSON.typeof(jsonVar) can be used to get the type of the var
      if (JSON.typeof(myObject) == "undefined") {
        Serial.println("Parsing input failed!");
        return;
      }
    
      Serial.print("JSON object = ");
      Serial.println(myObject);
    
      // myObject.keys() can be used to get an array of all the keys in the object
      JSONVar keys = myObject.keys();
    
      for (int i = 0; i < keys.length(); i++) {
        JSONVar value = myObject[keys[i]];
        Serial.print(keys[i]);
        Serial.print(" = ");
        Serial.println(value);
        sensorReadingsArr[i] = double(value);
      }
      Serial.print("1 = ");
      Serial.println(sensorReadingsArr[0]);
      Serial.print("2 = ");
      Serial.println(sensorReadingsArr[1]);
      Serial.print("3 = ");
      Serial.println(sensorReadingsArr[2]);
    }
    else {
      Serial.println("WiFi Disconnected");
    }
    lastTime = millis();
  }
}

String httpGETRequest(const char* serverName) {
  HTTPClient http;
    
  // Your IP address with path or Domain name with URL path 
  http.begin(serverName);
  
  // Send HTTP POST request
  int httpResponseCode = http.GET();
  
  String payload = "{}"; 
  
  if (httpResponseCode>0) {
    Serial.print("HTTP Response code: ");
    Serial.println(httpResponseCode);
    payload = http.getString();
  }
  else {
    Serial.print("Error code: ");
    Serial.println(httpResponseCode);
  }
  // Free resources
  http.end();

  return payload;
}

View raw code

Setting your serverName

Enter your domain name or Node-RED IP address, so the ESP requests the sensor readings that will be retrieved in a JSON object.

String serverName = "http://192.168.1.106:1880/get-sensor";

Now, upload the code to your board.

HTTP GET Request (JSON Object)

In the loop(), call the httpGETRequest() function to make the HTTP GET request:

sensorReadings = httpGETRequest(serverName);

The httpGETRequest() function makes a request to Node-RED address http://192.168.1.106:1880/get-sensor and it retrieves a string with a JSON object.

String httpGETRequest(const char* serverName) {
  HTTPClient http;

  // Your IP address with path or Domain name with URL path 
  http.begin(serverName);

  // Send HTTP POST request
  int httpResponseCode = http.GET();

  String payload = "{}"; 

  if (httpResponseCode>0) {
    Serial.print("HTTP Response code: ");
    Serial.println(httpResponseCode);
    payload = http.getString();
  }
  else {
    Serial.print("Error code: ");
    Serial.println(httpResponseCode);
  }
  // Free resources
  http.end();

  return payload;
}

Decoding JSON Object

To get access to the values, decode the JSON object and store all values in the sensorReadingsArr array.

JSONVar myObject = JSON.parse(sensorReadings);

// JSON.typeof(jsonVar) can be used to get the type of the var
if (JSON.typeof(myObject) == "undefined") {
  Serial.println("Parsing input failed!");
  return;
}

Serial.print("JSON object = ");
Serial.println(myObject);

// myObject.keys() can be used to get an array of all the keys in the object
JSONVar keys = myObject.keys();

for (int i = 0; i < keys.length(); i++) {
  JSONVar value = myObject[keys[i]];
  Serial.print(keys[i]);
  Serial.print(" = ");
  Serial.println(value);
  sensorReadingsArr[i] = double(value);
}
Serial.print("1 = ");
Serial.println(sensorReadingsArr[0]);
Serial.print("2 = ");
Serial.println(sensorReadingsArr[1]);
Serial.print("3 = ");
Serial.println(sensorReadingsArr[2]);

HTTP GET Demonstration

After uploading the code, open the Arduino IDE and you’ll see that it’s receiving the following JSON data:

{"value1":24.25,"value2":49.54,"value3":1005.14}

Then, you print the decoded JSON object in the Arduino IDE Serial Monitor.

For debugging purposes, the requested information is also printed in the Node-RED debug window.

3. ESP32 HTTP POST: URL Encoded, JSON Data Object, Plain Text

Finally, you’ll learn how to make an HTTP POST request with an ESP32.

With this example, your ESP32 can make HTTP POST requests using three different types of body requests: URL encoded, JSON object or plain text. These are the most common methods and should integrate with most APIs or web services.

HTTP POST ESP32 URL Encoded JSON Object Data Plain Text

Copy the next sketch to your Arduino IDE (type your SSID and password):

/*
  Rui Santos
  Complete project details at Complete project details at https://RandomNerdTutorials.com/esp32-http-get-post-arduino/

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files.

  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
*/

#include <WiFi.h>
#include <HTTPClient.h>

const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";

//Your Domain name with URL path or IP address with path
const char* serverName = "http://192.168.1.106:1880/update-sensor";

// the following variables are unsigned longs because the time, measured in
// milliseconds, will quickly become a bigger number than can be stored in an int.
unsigned long lastTime = 0;
// Timer set to 10 minutes (600000)
//unsigned long timerDelay = 600000;
// Set timer to 5 seconds (5000)
unsigned long timerDelay = 5000;

void setup() {
  Serial.begin(115200);

  WiFi.begin(ssid, password);
  Serial.println("Connecting");
  while(WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to WiFi network with IP Address: ");
  Serial.println(WiFi.localIP());
 
  Serial.println("Timer set to 5 seconds (timerDelay variable), it will take 5 seconds before publishing the first reading.");
}

void loop() {
  //Send an HTTP POST request every 10 minutes
  if ((millis() - lastTime) > timerDelay) {
    //Check WiFi connection status
    if(WiFi.status()== WL_CONNECTED){
      HTTPClient http;
      
      // Your Domain name with URL path or IP address with path
      http.begin(serverName);

      // Specify content-type header
      http.addHeader("Content-Type", "application/x-www-form-urlencoded");
      // Data to send with HTTP POST
      String httpRequestData = "api_key=tPmAT5Ab3j7F9&sensor=BME280&value1=24.25&value2=49.54&value3=1005.14";           
      // Send HTTP POST request
      int httpResponseCode = http.POST(httpRequestData);
      
      // 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\"}");

      // If you need an HTTP request with a content type: text/plain
      //http.addHeader("Content-Type", "text/plain");
      //int httpResponseCode = http.POST("Hello, World!");
     
      Serial.print("HTTP Response code: ");
      Serial.println(httpResponseCode);
        
      // Free resources
      http.end();
    }
    else {
      Serial.println("WiFi Disconnected");
    }
    lastTime = millis();
  }
}

View raw code

Setting your serverName

Enter your domain name or Node-RED IP address, so the ESP posts sample sensor readings.

String serverName = "http://192.168.1.106:1880/update-sensor";

Now, upload the code to your board.

HTTP POST URL Encoded

To make an HTTP POST request of type URL encoded, like this

POST /update-sensor HTTP/1.1
Host: 192.168.1.106:1880
api_key=tPmAT5Ab3j7F9&sensor=BME280&value1=24.25&value2=49.54&value3=1005.14
Content-Type: application/x-www-form-urlencoded

You need to run the following in your Arduino code:

// Your Domain name with URL path or IP address with path
http.begin(serverName);

// Specify content-type header
http.addHeader("Content-Type", "application/x-www-form-urlencoded");

// Data to send with HTTP POST
String httpRequestData = "api_key=tPmAT5Ab3j7F9&sensor=BME280&value1=24.25&value2=49.54&value3=1005.14";

// Send HTTP POST request
int httpResponseCode = http.POST(httpRequestData);

HTTP POST JSON Object

Or if you prefer to make an HTTP POST request with a JSON object:

POST /update-sensor HTTP/1.1
Host: example.com
{api_key: "tPmAT5Ab3j7F9", sensor_name: "BME280", temperature: 24.25; humidity: 49.54; pressure: 1005.14}
Content-Type: application/json

Use the next snippet:

http.addHeader("Content-Type", "application/json");

int httpResponseCode = http.POST("{\"api_key\":\"tPmAT5Ab3j7F9\",\"sensor\":\"BME280\",\"value1\":\"24.25\",\"value2\":\"49.54\",\"value3\":\"1005.14\"}");

HTTP Plain Text

If you want to send plain text or a value, use the following:

http.addHeader("Content-Type", "text/plain");

int httpResponseCode = http.POST("Hello, World!");

Note: the Node-RED flow we’re using (web service) is not setup to receive plain text, but if the API that you plan to integrate only accepts plain text or a value, you can use the previous snippet.

HTTP POST Demonstration

In the Node-RED debug window, you can view that your ESP is making an HTTP POST request every 5 seconds.

And in this example, those values are also sent to 3 Gauges and are displayed in Node-RED Dashboard:

http://raspberry-pi-ip-address:1880/ui

Wrapping Up

In this tutorial you’ve learned how to integrate your ESP32 with online services using HTTP GET and HTTP POST requests.

HTTP GET and HTTP POST are commonly used in most web services and APIs. These can be useful in your projects to: publish your sensor readings to a web service like IFTTT, ThingSpeak; to an ESP32 or Raspberry Pi web server or to your own server; to request data from the internet or from your database, and much more.

If you’re using an ESP8266 board, read: Guide for ESP8266 NodeMCU HTTP GET and HTTP Post Requests.

You might also like reading:

I hope you liked this project. If you have any questions, post a comment below and we’ll try to get back to you.

If you like ESP32, you might consider enrolling in our course “Learn ESP32 with Arduino IDE“. You can also access our free ESP32 resources here.

Thank you for reading.


Learn how to program and build projects with the ESP32 and ESP8266 using MicroPython firmware DOWNLOAD »

Learn how to program and build projects with the ESP32 and ESP8266 using MicroPython firmware DOWNLOAD »


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16 thoughts on “ESP32 HTTP GET and HTTP POST with Arduino IDE (JSON, URL Encoded, Text)”

  1. Hey guys,

    It’s a very good thing that you’re finally covering that part. The other day I was wondering why you didn’t put more emphasis on the specifics of communications that use the HTTP[S] protocol.

    In particular, the possibility of transporting structured data in JSON format. And I was going to talk about this in one of my next tutorials. But here it is, it’s done.

    And you could also take the opportunity to talk about the excellent Postman tool that greatly facilitates the development and introspection of HTTP APIs…

    https://www.postman.com/

    See you soon,
    Steph

    Reply
    • Hi Steph.
      You’re right.
      We should have published about this subject earlier.
      Thank you for your suggestion.
      Regards,
      Sara

      Reply
    • Hi Miguel.
      There are also other HTTP methods: like HTTP PUT, HTTP DELETE, HTTP PATCH
      But the ones we talked about in this tutorial are the most relevant for the ESP32.
      Thank you for your comment.

      Reply
  2. Hi, some bugs on BLOG

    JSON format, need quotes and node-red JSON name fields that dont match!

    Reply
    • Hello Miguel,
      The guide is correct, for that Node-RED the HTTP POST request is the following (api_key, sensor, value1, value2, value3): https://github.com/RuiSantosdotme/Random-Nerd-Tutorials/blob/master/Projects/ESP32/HTTP/ESP32_HTTP_POST.ino

      // Specify content-type header
      http.addHeader(“Content-Type”, “application/x-www-form-urlencoded”);
      // Data to send with HTTP POST
      String httpRequestData = “api_key=tPmAT5Ab3j7F9&sensor=BME280&value1=24.25&value2=49.54&value3=1005.14”;
      // Send HTTP POST request
      int httpResponseCode = http.POST(httpRequestData);

      Or in JSON

      // 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\”}”);

      So, the Node-RED flow needs to be:

      var msg0 = { payload: msg.payload.api_key };
      var msg1 = { payload: msg.payload.sensor };
      var msg2 = { payload: msg.payload.value1 };
      var msg3 = { payload: msg.payload.value2 };
      var msg4 = { payload: msg.payload.value3 };

      return [msg0, msg1, msg2, msg3, msg4];

      Reply
      • Thanks For this excellent tutorial.

        How to pass variable in JSON format .

        http.POST(“{\”api_key\”:\”tPmAT5Ab3j7F9\”,\”sensor\”:\”BME280\”,\”value1\”:variable,\”value2\”:variable,\”value3\”:variable}”);

        Reply
  3. Does anyone know how I can solve this problem?
    ‘JSONVar’ was not declared in this scope
    JSONVar myObject = JSON.parse(sensorReadings);

    Reply
  4. hi thank you for making this tutorial, its very helpful.

    but i was wondering would i be able to get a response from web server without raspberry pi, can i replace that with Arduino?

    Reply
  5. also, instead of getting a response from NODE_RED, can i use a web server that i built following this tutorial?? https://randomnerdtutorials.com/esp32-dht11-dht22-temperature-humidity-web-server-arduino-ide/

    i tried this, but failed, in my arduino serial monotor, it shows the folloeing msg
    Error code: -1
    13:41:28.031 -> {}
    13:41:28.031 -> JSON object = {}
    13:41:28.031 -> 1 = 0.00
    13:41:28.031 -> 2 = 0.00
    13:41:28.031 -> 3 = 0.00
    13:41:33.036 -> Error code: -1
    13:41:33.036 -> {}
    13:41:33.036 -> JSON object = {}
    13:41:33.036 -> 1 = 0.00
    13:41:33.036 -> 2 = 0.00
    13:41:33.036 -> 3 = 0.00

    Reply

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