Ask HN: Webhooks provider for managing subscriptions and emitting callbacks?

I've been trying to find a software package (docker image, npm module, ruby app, etc) that provides:

  - An API and preferably a web UI for adding webhook callback URLs for events
  - A backend that lets me feed in events and will deliver these as webhook callbacks to the registered subscribers, possibly with re-tries via a queue, etc.

Does something like this exists? All I've managed to find are a lot of libraries and frameworks for receiving webhooks, not sending them.

The few I've found seem quite bare bones and/or unmaintained:

  - https://github.com/progrium/hookah
  - https://github.com/roccomuso/node-webhooks

Have I missed something? Is this usually part of the delivery side of a generic message queue framework?

Thanks for any pointers!