ntfy.sh
Send push notifications to your phone or desktop using PUT/POST
...The service can be used through the public ntfy.sh instance or self-hosted on private infrastructure. It is useful for server alerts, cron job results, monitoring notifications, CI/CD updates, and personal automation. ntfy includes web, mobile, and command-line clients, making it accessible across different environments. Its main value is providing lightweight, open-source notifications without forcing users into a heavy messaging platform or paid push service.