ESP8266 - HTTP Request

This tutorial instructs you how to use ESP8266 to make HTTP request to web server, API, or Web service. In detail, You will learn:

How to use ESP8266 to make HTTP request (GET and POST)
How to include the sensor's data into HTTP request

Hardware Preparation

1	×	ESP8266 NodeMCU
1	×	Micro USB Cable
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) DC Power Jack
1	×	(Optional) Screw Terminal Expansion Board for ESP8266

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables.

Basic Concepts of Web Client and Web Server

There are some basic concepts of web such as: web address (URL), hostname, pathname, query string, HTTP Request... You can learn detailed about them in HTTP tutorial

How to Make an HTTP Request

Include libraries

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

Declare WiFi SSID and password

const char WIFI_SSID[] = "YOUR_WIFI_SSID"; // CHANGE IT const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD"; // CHANGE IT

Declare hostname, pathname, query string

String HOST_NAME = "http://YOUR_DOMAIN.com"; // CHANGE IT String PATH_NAME = "/products/arduino"; // CHANGE IT //String PATH_NAME = "/products/arduino.php"; // CHANGE IT String queryString = "temperature=26&humidity=70"; // OPTIONAL

Declare a HTTP client object

HTTPClient http;

If connected to server, and send HTTP request. For example, HTTP GET

http.begin(HOST_NAME + PATH_NAME); //HTTP int httpCode = http.GET();

Read the response data from web server

// httpCode will be negative on error if (httpCode > 0) { // file found at server if (httpCode == HTTP_CODE_OK) { String payload = http.getString(); Serial.println(payload); } else { // HTTP header has been send and Server response header has been handled Serial.printf("[HTTP] GET... code: %d\n", httpCode); } } else { Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str()); } http.end();

How to include data into HTTP request

We can send data to the web server by including data into HTTP request. The data format depends on HTTP request method:

For HTTP GET request

Data can be only sent in query string on the pathname.

HTTP POST request

Data can be sent NOT ONLY in query string format BUT ALSO any other format such as Json, XML, image ...
Data is put in HTTP request body.

Let's learn how to send data in query string format for both HTTP GET and POST

Create a query string

int temp = // from sensor int humi = // from sensor String queryString = String("temperature=") + String(temp) + String("&humidity=") + String(humi);

HTTP GET: add query string to pathname

http.begin(HOST_NAME + PATH_NAME + "?" + queryString); http.addHeader("Content-Type", "application/x-www-form-urlencoded"); int httpCode = http.GET();

HTTP POST: put query string in HTTP body

http.begin(HOST_NAME + PATH_NAME); http.addHeader("Content-Type", "application/x-www-form-urlencoded"); int httpCode = http.POST(queryString);

For both GET and POST, read the response data from web server

// httpCode will be negative on error if (httpCode > 0) { // file found at server if (httpCode == HTTP_CODE_OK) { String payload = http.getString(); Serial.println(payload); } else { // HTTP header has been send and Server response header has been handled Serial.printf("[HTTP] GET/POST... code: %d\n", httpCode); } } else { Serial.printf("[HTTP] GET/POST... failed, error: %s\n", http.errorToString(httpCode).c_str()); } http.end();

Complete ESP8266 Code for Making HTTP Request

The blow is the complete ESP8266 code for making HTTP GET/POST request

/* * This ESP8266 NodeMCU code was developed by newbiely.com * * This ESP8266 NodeMCU code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp8266/esp8266-http-request */ #include <ESP8266WiFi.h> #include <ESP8266HTTPClient.h> const char WIFI_SSID[] = "YOUR_WIFI_SSID"; // CHANGE IT const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD"; // CHANGE IT String HOST_NAME = "http://YOUR_DOMAIN.com"; // CHANGE IT String PATH_NAME = "/products/arduino.php"; // CHANGE IT WiFiClient client; // Create a WiFiClient object HTTPClient http; void setup() { Serial.begin(9600); WiFi.begin(WIFI_SSID, WIFI_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()); http.begin(client, HOST_NAME + PATH_NAME); //HTTP int httpCode = http.GET(); // httpCode will be negative on error if (httpCode > 0) { // file found at server if (httpCode == HTTP_CODE_OK) { String payload = http.getString(); Serial.println(payload); } else { // HTTP header has been sent and Server response header has been handled Serial.printf("[HTTP] GET... code: %d\n", httpCode); } } else { Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str()); } http.end(); } void loop() { // Your loop code here (if needed) }

Complete ESP8266 Code for Making HTTP GET Request with data

/* * This ESP8266 NodeMCU code was developed by newbiely.com * * This ESP8266 NodeMCU code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp8266/esp8266-http-request */ #include <ESP8266WiFi.h> #include <ESP8266HTTPClient.h> const char WIFI_SSID[] = "YOUR_WIFI_SSID"; // CHANGE IT const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD"; // CHANGE IT String HOST_NAME = "http://YOUR_DOMAIN.com"; // CHANGE IT String PATH_NAME = "/products/arduino"; // CHANGE IT //String PATH_NAME = "/products/arduino.php"; // CHANGE IT String queryString = "temperature=26&humidity=70"; void setup() { Serial.begin(9600); WiFi.begin(WIFI_SSID, WIFI_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()); WiFiClient client; // Create a WiFiClient object HTTPClient http; http.begin(client, HOST_NAME + PATH_NAME + "?" + queryString); http.addHeader("Content-Type", "application/x-www-form-urlencoded"); int httpCode = http.GET(); // httpCode will be negative on error if (httpCode > 0) { // file found at the server if (httpCode == HTTP_CODE_OK) { String payload = http.getString(); Serial.println(payload); } else { // HTTP header has been sent, and Server response header has been handled Serial.printf("[HTTP] GET... code: %d\n", httpCode); } } else { Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str()); } http.end(); } void loop() { // Your loop code here (if needed) }

Complete ESP8266 Code for Making HTTP POST Request with data

/* * This ESP8266 NodeMCU code was developed by newbiely.com * * This ESP8266 NodeMCU code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp8266/esp8266-http-request */ #include <ESP8266WiFi.h> #include <ESP8266HTTPClient.h> const char WIFI_SSID[] = "YOUR_WIFI_SSID"; // CHANGE IT const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD"; // CHANGE IT String HOST_NAME = "http://YOUR_DOMAIN.com"; // CHANGE IT String PATH_NAME = "/products/arduino"; // CHANGE IT //String PATH_NAME = "/products/arduino.php"; // CHANGE IT String queryString = "temperature=26&humidity=70"; void setup() { Serial.begin(9600); WiFi.begin(WIFI_SSID, WIFI_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()); WiFiClient client; // Create a WiFiClient object HTTPClient http; http.begin(client, HOST_NAME + PATH_NAME); http.addHeader("Content-Type", "application/x-www-form-urlencoded"); int httpCode = http.POST(queryString); // httpCode will be negative on error if (httpCode > 0) { // file found at server if (httpCode == HTTP_CODE_OK) { String payload = http.getString(); Serial.println(payload); } else { // HTTP header has been sent and Server response header has been handled Serial.printf("[HTTP] POST... code: %d\n", httpCode); } } else { Serial.printf("[HTTP] POST... failed, error: %s\n", http.errorToString(httpCode).c_str()); } http.end(); } void loop() { // Your loop code here (if needed) }

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