TopicPush: notifications to your phone with a plain HTTP request.

1. Open the TopicPush app. It creates a topic for you (or add your own).
2. Publish to it from anywhere:

   curl -d "Backup done" https://topicpush.com/<topic>
   curl -H "Title: Nike Dunk 42" -H "Image: https://picsum.photos/800/450" -H "Click: https://example.com" -d "45 EUR" https://topicpush.com/<topic>
   curl -H "content-type: application/json" -d '{"title":"Hello","message":"It works","image":"https://…","click":"https://…","priority":"high"}' https://topicpush.com/<topic>
   curl "https://topicpush.com/<topic>/publish?title=Hello&message=From+a+link"

Options (query string, header, or X- header): title|t, message|m, image|attach|a, click|url, priority|p (high, or low: no sound, Notification Center only), actions, detail (a line shown only when the notification is expanded).

Buttons (up to 4), ntfy-style. "http" calls the URL from the phone without opening the app; "view" opens it.
On iPhone, an "http" button pressed in the expanded notification shows the answer there: the JSON "message" field, or the first line of a text answer. Such a request carries the header X-TopicPush-Inline: 1, so your server can skip a separate result notification.
   curl -H "Actions: http, Open door, https://example.com/door, method=POST, icon=lock.open; view, Camera, https://example.com/cam" -d "Someone rang" https://topicpush.com/<topic>
   JSON: "actions":[{"action":"http","label":"Open door","url":"https://…","method":"POST","headers":{"Authorization":"…"},"body":"…","icon":"lock.open"}]
   icon: an SF Symbol name. input: the button asks for a line of text first, which replaces {input} in the URL or body, or is sent as the body (a GET button must put {input} in its URL):
   JSON: {"action":"http","label":"Reply","url":"https://…","input":{"placeholder":"Your answer","button":"Send"}}    header: input.placeholder=Your answer

Photo carousel (iPhone: long-press the notification and swipe), up to 10:
   curl -H "Images: https://…/1.jpg,https://…/2.jpg" -d "3 photos" https://topicpush.com/<topic>      JSON: "images":["https://…","https://…"]
Any other JSON body is delivered as the message text.

Read a topic: GET https://topicpush.com/<topic>/json?since=<ms or ISO>&limit=100  (comma-separate several topics)
Public page with subscribe link and QR code: https://topicpush.com/<topic>

A topic name is its own password: anyone who knows it can publish and read. Use a long random one.

Channels (read by anyone, published by you only):
   curl -X POST -H "content-type: application/json" -d '{"title":"My drops","description":"…"}' https://topicpush.com/<topic>/claim   → returns a key, shown once
   curl -H "Authorization: Bearer <key>" -d "New drop" https://topicpush.com/<topic>      (or ?key=<key> on a link)
   curl -X PATCH -H "Authorization: Bearer <key>" -d '{"title":"…"}' https://topicpush.com/<topic>/info
   curl -X POST -H "Authorization: Bearer <key>" https://topicpush.com/<topic>/key      → new key, the old one stops working
Topic names: letters, digits, - and _, up to 64 characters. Messages are kept 30 days.