Wouldn't it be possible for Zulip to go this route as well?
I think it's reasonable for Zulip to ask for compensation for access to these gateways, since Apple and Google do not make them available to end users free of charge, and the burden of responsibility to ensure that these systems aren't abused is on them. Also, the fact that they offer mobile push notifications for any self hosted server of up to 10 users is pretty generous, and there seems to be a Community plan option for larger servers that includes "groups of friends" as a qualifier. It really seems they're offering quite a bit.
On its own notification to your device will happen eventually when the ntfy app on your phone wakes up and polls. Pull, not push.
My ntfy server has a config line for an upstream, which is a service that then uses push. Basically it’s self hosted and handing off push.
I don't mean to cast aspersions on the developers—I respect everybody's right to try to get paid for good work, and this looks like good work. I am just not convinced it's the right option for my specific needs.
Nope. On iOS the flow is:
1. Generate a "push token" on the device (with the user's approval).
2. Send this token to your server.
3. Now you can send notifications to the device via this token. Your server needs to authenticate itself with Apple, and this requires an Apple account. But it's not linked to an individual app.
The situation is different on Android. Google went out of their way to make it impossible to customize `google-services.json` at runtime. So the built-in "easy" flow won't work. But notifications ultimately work using veeeeery obfuscated remote procedure calls to Google Play Services and you can run them manually. I need to do a write-up about this....