ESP32 Project #8 Wi-Fi Controlling Devices

Hello! I’m back :) On this project I’ll show you how to develop a controlling system with Wi-Fi communication to turn on and turn off the LED with a web server.

  • The web server will control the LEDs on the GPIO 26 and 27.
  • ESP32 web server can be accessed by typing the ESP32 IP address.
  • Turn on/off the LEDs by clicking the buttons on the web server.

To do this project, I need:

  • ESP32 board
  • 2 LEDs
  • 330 Ohm resistors
  • Jumper wires (male to male)
  • Breadboard
  • USB cable

First follow this schematic from randomnerdtutorials.


This is the raw code provided on the tutorial, but I want to make some changes.

Rui Santos
Complete project details at

// Load Wi-Fi library
#include <WiFi.h>

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

// Set web server port number to 80
WiFiServer server(80);

// Variable to store the HTTP request
String header;

// Auxiliar variables to store the current output state
String output26State = "off";
String output27State = "off";

// Assign output variables to GPIO pins
const int output26 = 26;
const int output27 = 27;

// Current time
unsigned long currentTime = millis();
// Previous time
unsigned long previousTime = 0;
// Define timeout time in milliseconds (example: 2000ms = 2s)
const long timeoutTime = 2000;

void setup() {
// Initialize the output variables as outputs
pinMode(output26, OUTPUT);
pinMode(output27, OUTPUT);
// Set outputs to LOW
digitalWrite(output26, LOW);
digitalWrite(output27, LOW);

// Connect to Wi-Fi network with SSID and password
Serial.print("Connecting to ");
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
// Print local IP address and start web server
Serial.println("WiFi connected.");
Serial.println("IP address: ");

void loop(){
WiFiClient client = server.available(); // Listen for incoming clients

if (client) { // If a new client connects,
currentTime = millis();
previousTime = currentTime;
Serial.println("New Client."); // print a message out in the serial port
String currentLine = ""; // make a String to hold incoming data from the client
while (client.connected() && currentTime - previousTime <= timeoutTime) { // loop while the client's connected
currentTime = millis();
if (client.available()) { // if there's bytes to read from the client,
char c =; // read a byte, then
Serial.write(c); // print it out the serial monitor
header += c;
if (c == '\n') { // if the byte is a newline character
// if the current line is blank, you got two newline characters in a row.
// that's the end of the client HTTP request, so send a response:
if (currentLine.length() == 0) {
// HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
// and a content-type so the client knows what's coming, then a blank line:
client.println("HTTP/1.1 200 OK");
client.println("Connection: close");

// turns the GPIOs on and off
if (header.indexOf("GET /26/on") >= 0) {
Serial.println("GPIO 26 on");
output26State = "on";
digitalWrite(output26, HIGH);
} else if (header.indexOf("GET /26/off") >= 0) {
Serial.println("GPIO 26 off");
output26State = "off";
digitalWrite(output26, LOW);
} else if (header.indexOf("GET /27/on") >= 0) {
Serial.println("GPIO 27 on");
output27State = "on";
digitalWrite(output27, HIGH);
} else if (header.indexOf("GET /27/off") >= 0) {
Serial.println("GPIO 27 off");
output27State = "off";
digitalWrite(output27, LOW);

// Display the HTML web page
client.println("<!DOCTYPE html><html>");
client.println("<head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">");
client.println("<link rel=\"icon\" href=\"data:,\">");
// CSS to style the on/off buttons
// Feel free to change the background-color and font-size attributes to fit your preferences
client.println("<style>html { font-family: Helvetica; display: inline-block; margin: 0px auto; text-align: center;}");
client.println(".button { background-color: #4CAF50; border: none; color: white; padding: 16px 40px;");
client.println("text-decoration: none; font-size: 30px; margin: 2px; cursor: pointer;}");
client.println(".button2 {background-color: #555555;}</style></head>");

// Web Page Heading
client.println("<body><h1>ESP32 Web Server</h1>");

// Display current state, and ON/OFF buttons for GPIO 26
client.println("<p>GPIO 26 - State " + output26State + "</p>");
// If the output26State is off, it displays the ON button
if (output26State=="off") {
client.println("<p><a href=\"/26/on\"><button class=\"button\">ON</button></a></p>");
} else {
client.println("<p><a href=\"/26/off\"><button class=\"button button2\">OFF</button></a></p>");

// Display current state, and ON/OFF buttons for GPIO 27
client.println("<p>GPIO 27 - State " + output27State + "</p>");
// If the output27State is off, it displays the ON button
if (output27State=="off") {
client.println("<p><a href=\"/27/on\"><button class=\"button\">ON</button></a></p>");
} else {
client.println("<p><a href=\"/27/off\"><button class=\"button button2\">OFF</button></a></p>");

// The HTTP response ends with another blank line
// Break out of the while loop
} else { // if you got a newline, then clear currentLine
currentLine = "";
} else if (c != '\r') { // if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
// Clear the header variable
header = "";
// Close the connection
Serial.println("Client disconnected.");

The change is on the SSID and password. I changed it to mine.

const char* ssid = "INSERT SSID";
const char* password = "INSERT PASSWORD";

Verify and upload the sketch. Open the serial monitor at 115200 baud rate and press ‘EN’ on the ESP32 board. This should be shown.

Serial Monitor

I tried to open the web server on my browser but this happened.

This site can’t be reached

Then I realized I still opened the serial monitor. I closed and reloaded the web server.

ESP32 Web Server

Finally I can access the web server!

To switch on the LEDs, just click the button and the LEDs will be on.

Actually I want to explore more about the code, especially the CSS. I redesigned the web server based on my preference and voila!


The modification can be seen below.

client.println("<style>html { font-family: Trebuchet MS, sans-serif; display: inline-block; margin: 0px auto; text-align: center;}");client.println(".button { background-color: #FF9ABB; border: none; border-radius: 10px; box-shadow: 0px 22.3363px 17.869px rgba(0, 0, 0, 0.0417275), 0px 12.5216px 10.0172px rgba(0, 0, 0, 0.035), 0px 6.6501px 5.32008px rgba(0, 0, 0, 0.0282725), 0px 2.76726px 2.21381px rgba(0, 0, 0, 0.0196802); color: black; padding: 16px 40px;");client.println("text-decoration: none; font-size: 30px; margin: 2px; cursor: pointer;}");client.println(".button2 {background-color: #E5E5E5; box-shadow: 0px 22.3363px 17.869px rgba(0, 0, 0, 0.0417275), 0px 12.5216px 10.0172px rgba(0, 0, 0, 0.035), 0px 6.6501px 5.32008px rgba(0, 0, 0, 0.0282725), 0px 2.76726px 2.21381px rgba(0, 0, 0, 0.0196802);}</style></head>");

On this project I learned how to connect ESP32 to a web server and accessed it by using ESP32 IP address. I also learned how to modify the web server using CSS. Hope this story can help and stay tune for the next projects!

Learner || Product and UX enthusiast