ESP32: from sensor to phone push in 20 lines

July 14, 2026 · 5 min read

The ESP32 costs a few euros and speaks Wi-Fi – the missing piece is usually “…and then it notifies my phone”. That piece is a single HTTPS POST. No MQTT broker, no Blynk account, no companion app to build.

The sketch

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

const char* WIFI_SSID = "your-wifi";
const char* WIFI_PASS = "your-pass";
const char* ENDPOINT  = "https://api.webhooky.app/YOUR_KEY";

void notify(const String& title, const String& message) {
  HTTPClient http;
  http.begin(ENDPOINT);
  http.addHeader("Content-Type", "application/json");
  http.POST("{\"title\":\"" + title + "\",\"message\":\"" + message + "\"}");
  http.end();
}

void setup() {
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  while (WiFi.status() != WL_CONNECTED) delay(250);
  notify("🔌 ESP32 online", "Booted and connected");
}

void loop() { /* read sensors, call notify() on events */ }

The ESP32 Arduino core validates api.webhooky.app's certificate against its bundled roots in recent versions; on older cores, use WiFiClientSecure with the ISRG Root X1 certificate (or setInsecure() while prototyping – just not forever).

Battery projects: notify, then sleep

notify("📬 Mailbox", "The mailbox was opened");
esp_deep_sleep_start();  // wake on GPIO next time

A reed switch on the mailbox lid, deep sleep between events – months on a battery, and a push the moment the mail arrives.

Project ideas

Doorbell / gate sensor – with "sound": "doorbell_1" it even sounds right.
Water leak sensor under the washing machine – error_1 and Important on.
Soil moisture – “water the tomatoes” once a threshold is crossed.
Freezer temperature – alarm before the ice cream melts.

Debounce your notifications

Sensors flap. Keep a lastSent timestamp and require a minimum gap (e.g. 5 minutes) per event type – your free 100 notifications (and your nerves) will thank you.

Get Webhooky

Free for your first 100 notifications – set up your endpoint in two minutes.