Published October 15, 2025 © MIT

🏠 Home Automation with ESP32: Building a 4-Channel Relay

Control up to 4 appliances using ESP32 via Web or App. Build your smart home easily — by YaranaIoT Guru

BeginnerFull instructions provided8 hours10

🏠 Home Automation with ESP32: Building a 4-Channel Relay

Things used in this project

Software apps and online services

Arduino IDE

Story

Priya wanted to make her house smart without spending thousands on commercial systems.After watching YaranaIoT Guru’s tutorial, she built her own 4-channel relay system using an ESP32 and basic coding.

Now, she can control her lights, fans, and even her coffee machine from her phone.Her family loves the convenience — and Priya proudly says:

“I built my smart home with the help of YaranaIoT Guru!” 🏡✨

“I built my smart home with the help of YaranaIoT Guru!” 🏡✨

💻 ESP32 Web Control Code

#include <WiFi.h>
#include <WebServer.h>

const char* ssid = "YourWiFi";
const char* password = "YourPassword";

int relays[] = {23, 22, 21, 19};
WebServer server(80);

void handleRoot() {
  String html = "<h2>ESP32 Home Automation</h2>";
  for (int i = 0; i < 4; i++) {
    html += "Relay " + String(i+1) + " ";
    html += "<a href=\"/on" + String(i+1) + "\">ON</a> ";
    html += "<a href=\"/off" + String(i+1) + "\">OFF</a><br>";
  }
  server.send(200, "text/html", html);
}

void setup() {
  Serial.begin(115200);
  for (int i = 0; i < 4; i++) pinMode(relays[i], OUTPUT);
  
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500); Serial.print(".");
  }
  Serial.println("\nConnected! IP: " + WiFi.localIP().toString());
  
  server.on("/", handleRoot);
  for (int i = 0; i < 4; i++) {
    server.on("/on" + String(i+1), [i]() {
      digitalWrite(relays[i], HIGH);
      server.send(200, "text/html", "Relay " + String(i+1) + " ON <a href='/'>Back</a>");
    });
    server.on("/off" + String(i+1), [i]() {
      digitalWrite(relays[i], LOW);
      server.send(200, "text/html", "Relay " + String(i+1) + " OFF <a href='/'>Back</a>");
    });
  }
  server.begin();
}

void loop() {
  server.handleClient();
}