Back to Projects
"tags": "ESP32relayWiFiweb controlhome automationIoT4-channel"

ESP32 WiFi Relay Controller

A professional 4-channel WiFi relay controller built on ESP32 with beautiful web interface. Control relays remotely through WiFi AP mode with real-time status display and IoTivate design system.

Overview

The WiFi Relay Controller is a professional 4-channel relay control system built on the ESP32 platform with a beautiful, responsive web interface.

Key Features

  • 4-channel relay control via GPIO pins
  • WiFi Access Point mode for immediate connection
  • Professional IoTivate dark theme web interface
  • Real-time relay status display
  • RESTful API endpoints for automation
  • Mobile-responsive design
  • mDNS discovery support
  • JSON status API with system information

Perfect For

  • Home automation projects
  • Remote device control
  • Industrial switching applications
  • IoT prototyping
  • Learning ESP32 web development

Simply flash the firmware, connect to the WiFi network, and control your relays through the intuitive web interface at http://192.168.4.1.

Parts List

ComponentQtyNotesBuy
ESP32 Development Board1—Buy
4-Channel 5V Relay Module1—Buy
Jumper Wires (Female-Female)1—Buy
Breadboard (optional)1—Buy

Circuit Diagram

Download
ESP32 WiFi Relay Controller Circuit Diagram

Build Guide

Prepare Components

Gather your ESP32 development board, 4-channel relay module, and jumper wires. Ensure your ESP32 is working by connecting it to your computer via USB.

Warning: Always disconnect power when making connections to avoid damage.

Wire the Relay Module

Connect the relay module to your ESP32:

  • Relay 1 IN → GPIO 5
  • Relay 2 IN → GPIO 18
  • Relay 3 IN → GPIO 19
  • Relay 4 IN → GPIO 21
  • VCC → 5V (or 3.3V depending on module)
  • GND → GND
Warning: Check your relay module voltage requirements (3.3V or 5V) before connecting VCC.

Flash the Firmware

Flash Firmware Directly: Connect your ESP32 device via USB, click the "Flash Firmware" button, and your browser will automatically load and flash the project's firmware using the Web Serial API - no drivers or software installation required. Pro users get additional batch flashing capabilities for production workflows with serial number injection and progress tracking across multiple devices.

Connect to WiFi Network

After flashing, the ESP32 will create a WiFi hotspot named WIFI_RELAY_XXXX (where XXXX are the last 4 digits of the MAC address). Connect to this network using password relay123.

Access Web Interface

Open your web browser and navigate to http://192.168.4.1. You should see the IoTivate-styled relay control interface with 4 relay cards, each showing the current status and a toggle button.

Test Relay Control

Click the toggle buttons to test each relay. You should hear the relay clicking and see the status change from OFF to ON. The web interface will refresh to show the new state.

Warning: Be careful when connecting high-voltage devices to relay outputs. Always follow electrical safety guidelines.

Firmware

v1.0.0

WiFi Relay Controller Firmware

  • 4-channel relay control
  • WiFi Access Point mode
  • Professional web interface
  • RESTful API endpoints
  • Real-time status display
  • Mobile-responsive design
  • mDNS discovery
  • JSON status API
Free