ifttt_button.ino

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>
// Change these to the WiFi credentials
#define WLAN_SSID "WIFINAME"
#define WLAN_PASS "PASSWORD"

#define BUTTON 4

void setup() {
  Serial.begin(115200);

  // Connect to WiFi
  WiFi.begin(WLAN_SSID, WLAN_PASS);
  Serial.println("");
  Serial.println("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(10);
  }
  Serial.println("");
  Serial.println("Connected!");

  pinMode(BUTTON, INPUT_PULLUP);
}

void loop() {
  // Read button
  int buttonValue = digitalRead(BUTTON);
  if (buttonValue == LOW) {
    Serial.println("Button pressed! Sending request to IFTTT...");
    if (WiFi.status() == WL_CONNECTED) {
      HTTPClient http;
      // Change the below address to the one from your IFTTT account.
      http.begin("http://maker.ifttt.com/trigger/button_pressed/with/key/yourKeyhere");
      int httpCode = http.GET();
      Serial.print("HTTP code: ");
      Serial.println(httpCode);
      if (httpCode == HTTP_CODE_OK) {
        Serial.println("Request sent!");
      }
      delay(2000);
      http.end();
    }
  }
}