Ask HN: Good tool to send personal notifications?

I need a simple service to send push notifications programmatically to my own phone. I don't want to make an entire app, but I am okay with (and know it will likely involve) downloading one. I don't want to use email or SMS. I want something like PagerDuty, but for myself. I want to send an API request and have my phone alert me the next second. Is there such a service?