NTFY part 2: Send notifications with ESP32 and Pico

For an index to all my stories click this text.

This is the second story about NTFY. The first story showed what NTFY is and how it can send notifications and messages to your Android smartphone from a PC dashboard.

This story shows how you can send notifications from your EP8266 or ESP32 in Arduino language (C++) to your phone, and how you can do that with a Raspberry Pi Pico in MicroPython.

So before you go on I recommend reading the previous story which you can find here: https://lucstechblog.blogspot.com/2026/05/notifications-with-ntfy.html

I'll start with sending a message from the Raspberry Pi Pico as a notification to a smartphone.

For your convenience I hereby give you the link to the NTFY website: https://ntfy.sh/

Limits and solution

First I hope you remember that with the free service NTFY there is a limit of 250 messages per day.
 
The messages remain for 12 hour on the server.
This means that if your phone is off, or has no internet connection, for 13 hours you will miss messages.

There are two solutions for this.
First you can get a paid subscription and then you get a lot more messages each day.
The second solution is to install your own NTFY server. You can do that on a Raspberry Pi (even the humble Zero) and then you can decide how many messages you can send per day  and how long they stay on the server.

Mind you: 250 messages per day is about 10 messages per hour which would be more than sufficient for most projects.

Nevertheless I chose the second solution and installed my own server. Maybe something for another story ........................

Sending a message from MicroPython with a Pico 

(Scroll down for the ESP32 arduino version)

We are going to do this the easy way. We are going to attach a button to the Pico and simulate that it is a door contact. Everytime the button is pressed the Pico will send a notification to the phone.

We are going to send an alarm with the text:

The door opened X times

The X will alter each time we press the button.

Let's start with the breadboard setup which is really easy.



It is just the Raspberry pi pico with a button attached to GP14. The button has a pull up resistor so the value is high (1) until we press the button. Then it gets low (0).

Here is the complete program.

import machine
import network
import urequests as requests
import time

button1 = machine.Pin(14, machine.Pin.IN)
dooropen = 0

# Router credentials
ssid = "YOUR-ROUTERS-NAME"
pw = "YOUR-PASSWORD"
print("Connecting to wifi...")

# wifi connection
wifi = network.WLAN(network.STA_IF)
wifi.active(True)
wifi.connect(ssid, pw)

# wait for connection
while not wifi.isconnected():
    pass

print("Connected. IP: ",str(wifi.ifconfig()[0], "\n"))

while True:
    if button1.value() == 0:
        dooropen = dooropen + 1
        sendstring ="The door opened " + str(dooropen) + " times"
        requests.post("http://ntfy.sh/lucstechblog",
        data= sendstring              
        )
        print("Data is send. dooropen = "+str(dooropen))
        time.sleep(3)

Let's have a look at the program in some detail.

import machine
import network
import urequests as requests
import time 

These are the libraries that are needed to get the program running. They are all included in the standard MicroPython distributions. So no need to download libraries.

button1 = machine.Pin(14, machine.Pin.IN)
dooropen = 0

The button is attached to GP14 and defined as a variable with the name button1. An extra variable with the name dooropen is defined. This will be used to count the number of times you press the button.

# Router credentials
ssid = "YOUR-ROUTERS-NAME"
pw = "YOUR-PASSWORD"
print("Connecting to wifi...")

# wifi connection
wifi = network.WLAN(network.STA_IF)
wifi.active(True)
wifi.connect(ssid, pw)

# wait for connection
while not wifi.isconnected():
    pass

print("Connected. IP: ",str(wifi.ifconfig()[0], "\n"))

Nothing special here. These are the standard program lines to connect the Pico to your router. Don't forget to replace YOUR-ROUTERS-NAME and YOUR-PASSWORD with the required values for your router.
When the connection is established you will find the Pico's IP number in MicroPython's shell.

while True:
    if button1.value() == 0:
        dooropen = dooropen + 1

The while loop is where the actual action takes place.
First the program tests if the button is pressed. If so then the variable dooropen is increased by 1.

        sendstring ="The door opened " + str(dooropen) + " times"

In this line we prepare the text that is going to be send.
This is the important line. Here you can fill in any information you like to send. If you would add a digital thermometer and put it's value in the variable temp you could alter the text like like this:

        sendstring ="The temperature is now " + str(temp) + " degrees"

On to the next part.

        requests.post("http://ntfy.sh/lucstechblog",
        data= sendstring              
        )

NTFY needs a post request in stead of the get requests which we normally use. We post to the site http://ntfy.sh/ and the topic is lucstechblog.

        print("Data is send. dooropen = "+str(dooropen))
        time.sleep(3)

Next we print a confirmation in the shell and wait a few seconds to make sure the request is send.

That is all.

The result.

Run the program. Press the button.



And this is what you'll see in Thonny's shell.



And here is how I got a notification in the top left corner of my phone's screen. My phone also gave an audio signal to draw my attention to the notification.



This is how the notification appeared on my phone's screen



And this is how it looks in the NTFY app on my phone.

At the same time the message appeared in the PC web version of NTFY.

Sending a message with an ESP32 in Arduino language (C++)

Just like we did with the Pico and MicroPython, we are going to do this the easy way. We are going to attach a button to the ESP32 and everytime the button is pressed the ESP32 will send a notification to the phone.

We are going to send an alarm with the text:

The button attached to the ESP32 was pressed X times.

The X will alter each time we press the button.

Let's start with the breadboard setup which is really easy.



It is just the ESP32 with a button attached to D22. The button has a pull up resistor so the value is high (1) until we press the button. Then it gets low (0).

Here is the complete program.

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

const char* ssid = "YOUR-ROUTERS-NAME";
const char* password = "PASSWORD";

//Where to send the notification
const char* ntfyurl = "http://ntfy.sh/lucstechblog";

const int buttonPin = 23;
int butpress = 0;

void setup() 
  {
  pinMode(buttonPin, INPUT);  
  
  Serial.begin(115200);

  WiFi.begin(ssid, password);
  Serial.println("Connecting");
  while(WiFi.status() != WL_CONNECTED) 
    {
      delay(500);
      Serial.print(".");
    }
  Serial.println("");
  Serial.print("Connected to WiFi network with IP Address: ");
  Serial.println(WiFi.localIP());
  }

void loop() 
{
    if (digitalRead(buttonPin) == LOW) 
      {
      butpress = butpress + 1;  
      if(WiFi.status()== WL_CONNECTED)
        { 
      WiFiClient client;
      HTTPClient http;
    
      // Your Domain name with URL path or IP address with path
      http.begin(client, ntfyurl);
      http.addHeader("Content-Type", "text/plain");
      
      // Build the text to send with HTTP POST:
      // The button attached to the ESP32 was pressed X times.
      String httpRequestData = "The button attached to the ESP32 was pressed "; 
      httpRequestData = httpRequestData + butpress;
      httpRequestData = httpRequestData + " times";  
      
      // Send HTTP POST request
      int httpResponseCode = http.POST(httpRequestData);
      
      Serial.print("The response we got : ");
      Serial.println(httpResponseCode);
        
      // Close connection
      http.end();

      // Wait before the next round
      delay (3);
        }
      }  
}

Lets look at some details in the program.

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

const char* ssid = "YOUR-ROUTERS-NAME";
const char* password = "PASSWORD";

//Where to send the notification
const char* nyfyurl = "http://ntfy.sh/lucstechblog";

const int buttonPin = 23;
int butpress = 0;

Nothing special here. The necessary libraries are loaded and The variables are defined. The variable ntfyurl is defined as http://ntfy.sh/lucstechblog which is the address of the NTFY server and the topic.

The setup() has nothing unusual.

The loop() is where the fun begins.

    if (digitalRead(buttonPin) == LOW)
      {
      butpress = butpress + 1;  
      if(WiFi.status()== WL_CONNECTED)
        {
      WiFiClient client;
      HTTPClient http;

The program continually tests if the button is pressed. If so the butpress variable is increased by 1 and the wifi and http clients are activated.

      // Your Domain name with URL path or IP address with path
      http.begin(client, ntfyurl);
      http.addHeader("Content-Type", "text/plain");

The http communication with the NTFY server is started with the previous defined ntfyurl. A header is sent first that identifies the data we are going to send as plain text.

      // Build the text to send with HTTP POST:
      // The button attached to the ESP32 was pressed X times.
      String httpRequestData = "The button attached to the ESP32 was pressed ";
      httpRequestData = httpRequestData + butpress;
      httpRequestData = httpRequestData + " times";

The text "The button attached to the ESP32 was pressed X times." is build here by combining several parts. One of the parts that is added is butpress which is the variable that counts how many times the button was pressed.

      // Send HTTP POST request
      int httpResponseCode = http.POST(httpRequestData);
      
      Serial.print("The response we got : ");
      Serial.println(httpResponseCode);
        
      // Close connection
      http.end();

The request is send as a http POST request with the previous defined httpRequestData. The request receives a response with an indication if it has succeeded. The response is then printed in the serial monitor. After sending the request the connection is closed.

      // Wait before the next round
      delay (3);

The program then waits for 3 seconds. This time can be shortened but a short delay is preferred to prevent detecting a bouncing button as a button press.

It is obvious that this code can easily be adapted to send sensor readings etc. etc. etc.



This is what the Serial Monitor shows. As you can see there are 4 responses with the number 200 that means that the request was received ok.



And here are the notifications I received. As you can see I subscribed to 6 topics. The topics were made just for testing.

Expansion

In this example I use the same topic all the time: lucstechblog. It is of course possible to create multiple topics. So a single Pico or ESP can send notifications to several topics. However you can also have multiple microcontrollers sending data to several topics.

In the above examples we send notifications with just one line of text. You can send notifications with multiple lines of text. The documentation of NTFY shows how to do this. You can find the documentation here: https://docs.ntfy.sh/

Even better: you can attach files to a notification. These can be text files but also pictures !! I have successfully experimented with sending pictures from C++ and from MicroPython. I can see a chat program coming up...........

You can have the Pico's and ESP's send notifications to several NTFY servers.
On the NTFY documents pages there is a list of public NFTY servers. You can find the docs and that list here: https://docs.ntfy.sh/integrations/

You can start your own private server. A Raspberry Pi is sufficient. Even a humble Raspberry Pi Zero will do.
Using your own private server does not expose your topics (if someone finds them) and their data to a general audience. It restricts the information to those you have given the information about the server and it's topics.
On a private server you can expand the lifetime of the messages from 12 hour to any timelimit that suits you. And the number of messages you can send per day can be limitless !!!

Not only can you send notifications but using the right API call you can also get all notifications that have been send with a certain topic from the server. This way you can have two-way conversation between microcontrollers. A microcontroller can retrieve the messages on a certain topic from the server, and can act on that, and then send a notification with the same or a different topic. You do need a private server for this.

If you want a story on sending multiple line notifications, sending a textfile or a picture with the notification, starting your own server on a Raspberry Pi or retrieving notifications from your private server please send me an email.

I can see loads of possibilities with NTFY and therefore already installed my own private server.

Till next time.
Have fun
Luc Volders

Delft Maker fair 2026

 For an index to all my stories click this text

Yesterday 8 may 2026 was the day of the Delft Maker fair.

At the university campus of the Technical University Delft there was a gathering of makers, students, creative minds and loads of visitors.
There were workshops, loads of demonstrations and some novelties.

A 2 meter high contraption with moving eyes, wings and all sorts of other moving parts with a working bubble blowing machine. It was moving around on wheels remote controlled by its maker.

Someone was making lamps from all kinds of vintage products like phones, photocams etc.

A life size build based on the "Theo Jansen "strandbeest". This version did not move on the wind like the original strandbeest but had large motors inside. You could sit on it and move it around with some controls.

3D printing everywhere. And the new hype is of course color printing.

And here is the first one I saw live: the Creality I7 Sparkx
Creality's answer to Bambu. A 4 color 3D printer priced (at this moment) for around 350 USD/Euro. I saw it working and I saw the quality: I want one !!!!!

And a lot of tinkering. Like this antique Singer sewing machine with a motor that drove the sewing part and X and Y Axis that moved the cloth. So you can use it as an embroidery machine. Arduino powered.

There were over 100 stands. There was a hydrogen racing car, a hyperloop, fablabs, cnc machines, laser engravers, workshops, demonstrations and loads more. And of course everywhere Arduino's, ESP32's, Raspberry Pi's and Pico's. Most part of it was outside and the weather was fantastic.

One thing I can not show you here but was really fun was an industrial coffee machine that was insulting everyone who tried to use it.

If you ever have the time to visit a MakerFair I urge you to do so. It gives your creative energy an enormous boost.

Till next time
have fun

Luc Volders

Notifications with NTFY

For an index to all my stories click this text.

When working with IOT projects several things can happen. A certain temperature is reached, movement is detected, a light is set on in a room, someone is at the door etc. etc.etc. When something like this happens you will want to get a notification. You can, of course, build a website on which values are shown. But that implies that you need to go to that website to look at the values.

It is more efficient when you get a notification (an alarm) on your smart phone.



A notification like this is put on the startscreen of your phone so it will always draw your attention.

There is a free service that you can use to get these notifications it is called NTFY
You can find the website here: https://ntfy.sh/

NTFY

NTFY is of course short for NoTiFY. It is a free service that you can use. 

There is a limit of 250 notifications per day for a free or anonymous account. That is 10 messages per hour !!!

If you need more than 250 messages per day then you need to get a paid subscription.

To use NTFY you need to download a (free) app on your phone or tablet. But there is also a desktop (PC) version that can receive messages but can also send messages.

To send notification messages to your phone, tablet or PC there is a simple to use API that can be used with Arduino (C++) and MicroPython.

For using the free version you do not have to log-in or make an account. You can just use it. That is a bit like dweet.

Another similarity to Dweet is that a message/notification consists of two parts: a topic and the message itself. To get the notifications on your Phone or PC you need to "subscribe" to that topic.
A topic might be for example "Alarm" and the message can be "The garage door is open". Another topic might be "Myhome" and a message could be "The temperature = 22 degrees"

You may create as many topics as you like as long as you do not exceed the limit of 250 messages. A topic is created automatic when you send a message with your microcontroller that includes a non existant topic.

And yet another similarity to Dweet is that (unless you have a paid account) the topics are public. This means that anybody can get your messages and notifications as long as they know the topic you are using.
So use a cryptic topicname like LV23kit where LV are my initials, 23 is the year (2023) and kit means that the messages concern my kitchen. Just be creative.

If you need private topics you will need to get a paid plan.

The big difference with Dweet is that NTFY can send notifications to your phone/tablet/pc. Dweet can not send them, you need to collect them yourself. So for sending alarms NTFY is the best option.

There is one extra option that might prove usefull. NTFY can also send emails. So you can get your messages in your mailbox. For alarms that is not really an option as you want an instant notification if something is wrong. However it might be usefull for some of you so I will show how to use this option. With the free version you can send 5 emails per day.

One more thing though. The messages/notifications are stored for 12 hours. After 12 hours the messages disappear.

NTFY on the PC

First thing we are going to do is to get NTFY on your PC. Well that is easy. Just point your browser to https://ntfy.sh/app and you're done.



This is how the webpage looks..



Click on + Subscribe to topic and a window opens that allows you to enter the name of a topic.
Like stated before, for an anonymous (and free account), topics are public so choose a topic name that others can not guess easily.



You can also click on GENERATE NAME and NTFY will generate a topic for you that closely resembles a password.
This will give you some better privacy and secrecy but is more difficult to use on multiple devices at the same time. If, for example, you are using NTFY at the same time on your PC and on your smart phone you will need to find a way to send this cryptic topic name to your phone.

I choose a topic name myself: lucstechblog

Then click SUBSCRIBE.



This is how your screen will look now. On the left there is a list of subscribed topics. At this moment there is just one: lucstechblog. In the center there is a message that no notifications have been send or received with this topic.

NTFY on the Android Phone

To get notifications we need to install the NFTY app from the playstore. You can find it here:
https://play.google.com/store/apps/details?id=io.heckel.ntfy
Or just search for NTFY in the app store.

Install the app and open it.

It looks almost the same as the PC version. 

Press the + at the bottom of the screen for subscribing to a topic. We will use the same topic: lucstechblog
A big difference from the PC version is that there is no option to have NTFY generate a topic for you. This is because the phone version is only used for receiving notifications.

We now have 1 subscription to a topic.

Sending a message from the PC

Click with your mouse on the subscribed topic (lucstechblog)

And at the bottom type a test message like I did. Then click on the small arrow next to the message.



The PC screen will inform you that the message is send.



And you will almost immediately get a notification on your phone.
This is the important part. This shows that we can get alarm messages and other important messages as a notification on our phone.



And the NFTY app will inform you that a notification has been received.
And shows message also in the app.

First steps done.

The first setup is done.

Make yourself comfortable with the concept and create some topics for yourself and play around a bit.

Next time we are going to send notifications from the ESP32 using Arduino language (C++) and from the Raspberry Pi Pico with MicroPython.

A few small tips

You can use the browser version next to the app on your Phone. Just point your browser to: https://ntfy.sh/app That way you can also send messages from the phone that will be received by the PC. You will not get notification alarms through the browser but you will still get them through the app.

You can use NTFY on multiple phones and tablets. As long as they all subscribe to the same topics, they will all get the same notifications/messages.

And please remember that you can make as many topics as you like but there is a limit of 250 messages per day for the free account. The messages are stored on the server for 12 hours after which they vanish.

Although you can create loads of topics it is better and easier to maintain if you just use a few topics and make the messages in the topics more verbal.

Next story covers how to send notifications from your ESP32 with Arduino language (C++) or Raspberry Pi Pico W with MicroPython

So Till next time
have fun


Luc Volders