Simplepush

Install the app and start sending push notifications immediately with no sign-up required.

Push notifications can be end-to-end encrypted and support actions for bidirectional communication.

10 notifications per month for free or $12.49 per year for unlimited push notifications.

You can then send notifications to your phone by visiting the following link where you replace "YourKey" with your Simplepush key which you receive after installing the app.
https://simplepu.sh/YourKey/message

See https://simplepush.io/integrations for integrations and library support.