ntfy

ntfy is a self-hosted pub-sub notification service for sending push notifications to your phone or desktop via simple HTTP PUT/POST requests, an open-source alternative to Pushover and Pushbullet. After deploying, set the NTFY_BASE_URL env var to your service's public URL (e.g. https://your-app.deployra.app) so the web app, attachments, and mobile clients work correctly, then redeploy. Messages and user accounts persist in SQLite at /data (NTFY_CACHE_FILE, NTFY_AUTH_FILE). Create users and access tokens with the ntfy user / ntfy token CLI inside the container.

Source: GitHub