Published October 13, 2025 © MIT

Change WiFi on ESP32 Without Re-uploading Code

Allow users to change Wi-Fi credentials at runtime using a captive-portal — no code re-upload needed

BeginnerProtip8 hours63

Change WiFi on ESP32 Without Re-uploading Code

Things used in this project

Hardware components

Arduino UNO

Software apps and online services

Arduino IDE

Story

Ek din Amit apne smart home project par kaam kar raha tha. Usne ESP32 se apne room ki lights aur fans control karne ka system banaya tha. Sab kuchh perfect chal raha tha — jab tak usne WiFi router change nahi kiya!

Naya router lagte hi ESP32 connect hona band ho gaya. Har baar code dubara upload karna padta tha. Amit pareshaan ho gaya. Tabhi usne YouTube par YaranaIoT Guru ka video dekha —“Change WiFi on ESP32 Without Re-uploading Code” 🔥

Us video se usne seekha ki kaise ek chhoti si library se ESP32 khud hi WiFi change kar sakta hai. Ab jab bhi WiFi badalta hai, Amit bas apne mobile se portal open karta hai, naya password dalta hai, aur device turant connect ho jata hai.

Amit ke words me —

“YaranaIoT Guru ne mera project truly smart bana diya!”

“YaranaIoT Guru ne mera project truly smart bana diya!”

Aur tab se Amit ka ghar ban gaya — ek Smart IoT Home.

💻 Arduino Code

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

Preferences preferences;
WebServer server(80);

String ssid = "";
String password = "";

void handleRoot() {
  String html = "<h2>ESP32 WiFi Setup Portal</h2><form action='/save'><input name='ssid' placeholder='SSID'><br><input name='pass' placeholder='Password'><br><input type='submit'></form>";
  server.send(200, "text/html", html);
}

void handleSave() {
  ssid = server.arg("ssid");
  password = server.arg("pass");
  
  preferences.begin("wifi-config", false);
  preferences.putString("ssid", ssid);
  preferences.putString("pass", password);
  preferences.end();
  
  String html = "<h3>Saved Successfully! Rebooting...</h3>";
  server.send(200, "text/html", html);
  delay(2000);
  ESP.restart();
}

void setup() {
  Serial.begin(115200);
  preferences.begin("wifi-config", true);
  ssid = preferences.getString("ssid", "");
  password = preferences.getString("pass", "");
  preferences.end();

  if (ssid != "") {
    WiFi.begin(ssid.c_str(), password.c_str());
    Serial.println("Connecting to saved WiFi...");
    for (int i = 0; i < 20; i++) {
      if (WiFi.status() == WL_CONNECTED) break;
      delay(500);
      Serial.print(".");
    }
  }

  if (WiFi.status() != WL_CONNECTED) {
    WiFi.softAP("ESP32_Setup");
    server.on("/", handleRoot);
    server.on("/save", handleSave);
    server.begin();
    Serial.println("AP Mode: ESP32_Setup");
  }
}

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