Hey HN, for my last side project of the year I decided to build a much needed piece of infrastructure for the Celo (https://celo.org) blockchain ecosystem, an event subscription service.

You can configure it to listen for events on certain contracts (some basic filtering functionality is provided so you don't spam yourself) and receive a webhook when your conditions are met.

It has an HTTP API so you can easily register events from your system and supports custom ABI parsing so you can receive decoded events.

This kind of system is crucial for running any service on top of a blockchain, some quick use cases that spring to mind are:

- building a Stripe like service on the blockchain and watching for transfers

- monitoring sign ups for an email welcome.

Looking forward to any feedback!