ntfy.sh | simple HTTP-based pub-sub
Ntfy (pronounce: notify) is a simple HTTP-based pub-sub notification service. It allows you to send notifications to your phone or desktop via scripts from any computer, entirely without signup or cost. It's also open source if you want to run your own.
There are many ways to use Ntfy. You can send yourself messages for all sorts of things: When a long process finishes or fails (a backup, a long rsync job, ...), or to notify yourself when somebody logs into your server(s). Or you may want to use it in your own app to distribute messages to subscribed clients. Endless possibilities 😀. Be sure to check out the example on GitHub!
Publishing messages
Publishing messages can be done via PUT or POST using. Topics are created on the fly by subscribing or publishing to them. Because there is no sign-up, the topic is essentially a password, so pick something that's not easily guessable.
Here's an example showing how to publish a message using curl:
curl -d "long process is done" ntfy.sh/mytopic
Here's an example in JS with fetch() (see full example):
fetch('https://ntfy.sh/mytopic', {
method: 'POST', // PUT works too
body: 'Hello from the other side.'
})
Subscribe to a topic
You can create and subscribe to a topic either in this web UI, or in your own app by subscribing to an EventSource, a JSON feed, or raw feed.
Subscribe in this Web UI
Subscribe to topics here and receive messages as desktop notification. Topics are not password-protected, so choose a name that's not easy to guess. Once subscribed, you can publish messages via PUT/POST.
Subscribe via Android App
You can use the Ntfy Android App to receive notifications directly on your phone. Just like the server, this app is also open source.
Subscribe via your app, or via the CLI
Using EventSource in JS, you can consume notifications like this (see full example):
const eventSource = new EventSource('https://ntfy.sh/mytopic/sse');
eventSource.onmessage = (e) => {
// Do something with e.data
};
You can also use the same /sse endpoint via curl or any other HTTP library:
$ curl -s ntfy.sh/mytopic/sse
event: open
data: {"id":"weSj9RtNkj","time":1635528898,"event":"open","topic":"mytopic"}
data: {"id":"p0M5y6gcCY","time":1635528909,"event":"message","topic":"mytopic","message":"Hi!"}
event: keepalive
data: {"id":"VNxNIg5fpt","time":1635528928,"event":"keepalive","topic":"test"}
To consume JSON instead, use the /json endpoint, which prints one message per line:
$ curl -s ntfy.sh/mytopic/json
{"id":"SLiKI64DOt","time":1635528757,"event":"open","topic":"mytopic"}
{"id":"hwQ2YpKdmg","time":1635528741,"event":"message","topic":"mytopic","message":"Hi!"}
{"id":"DGUDShMCsc","time":1635528787,"event":"keepalive","topic":"mytopic"}
Or use the /raw endpoint if you need something super simple (empty lines are keepalive messages):
$ curl -s ntfy.sh/mytopic/raw
This is a notification
Here's an example of how to use this endpoint to send desktop notifications for every incoming message:
while read msg; do
[ -n "$msg" ] && notify-send "$msg"
done < <(stdbuf -i0 -o0 curl -s ntfy.sh/mytopic/raw)
Other features
Fetching cached messages
Messages are cached on disk for {{.CacheDuration}} to account for network interruptions of subscribers. You can read back what you missed by using the since= query parameter. It takes either a duration (e.g. 10m or 30s), a Unix timestamp (e.g. 1635528757) or all (all cached messages).
curl -s "ntfy.sh/mytopic/json?since=10m"
Fetching cached messages
You can also just poll for messages if you don't like the long-standing connection using the poll=1 query parameter. The connection will end after all available messages have been read. This parameter can be combined with since= (defaults to since=all).
curl -s "ntfy.sh/mytopic/json?poll=1"
Subscribing to multiple topics
It's possible to subscribe to multiple topics in one HTTP call by providing a comma-separated list of topics in the URL. This allows you to reduce the number of connections you have to maintain:
$ curl -s ntfy.sh/mytopic1,mytopic2/json
{"id":"0OkXIryH3H","time":1637182619,"event":"open","topic":"mytopic1,mytopic2,mytopic3"}
{"id":"dzJJm7BCWs","time":1637182634,"event":"message","topic":"mytopic1","message":"for topic 1"}
{"id":"Cm02DsxUHb","time":1637182643,"event":"message","topic":"mytopic2","message":"for topic 2"}
FAQ
Isn't this like ...?
Who knows. I didn't do a lot of research before making this. It was fun making it.
Can I use this in my app? Will it stay free?
Yes. As long as you don't abuse it, it'll be available and free of charge. I do not plan on monetizing
the service.
What are the uptime guarantees?
Best effort.
What happens if there are multiple subscribers to the same topic?
As per usual with pub-sub, all subscribers receive notifications if they are
subscribed to a topic.
Will you know what topics exist, can you spy on me?
If you don't trust me or your messages are sensitive, run your own server. It's open source.
That said, the logs do not contain any topic names or other details about you.
Messages are cached for {{.CacheDuration}} to facilitate service restarts, message polling and to overcome
client network disruptions.
Why is Firebase used?
In addition to caching messages locally and delivering them to long-polling subscribers, all messages are also
published to Firebase Cloud Messaging (FCM) (if FirebaseKeyFile is set, which it is on ntfy.sh). This
is to facilitate instant notifications on Android.
Privacy policy
Neither the server nor the app record any personal information, or share any of the messages and topics with any outside service. All data is exclusively used to make the service function properly. The one exception is the Firebase Cloud Messaging (FCM) service, which is required to provide instant Android notifications (see FAQ for details).
The web server does not log or otherwise store request paths, remote IP addresses or even topics or messages, aside from a short on-disk cache (for {{.CacheDuration}}) to support service restarts.