Recently updated on npmjs.org, ActivePush is a web push service library for any STOMP broker:
ActivePush subscribes to a STOMP broker and relays messages with a specific push_id header to subscribed Socket.io clients. The message bodies are opaque to ActivePush, so the service is useful in a variety of applications.
-- ActivePush npm page
Unlike a lot of npm pages, ActivePush's page has a bunch of information on The architecture, configurations, production, usage and testing. There are plenty of STOMP brokers out there, and many brokers can add STOMP adapters (RabbitMQ for example).