Last year Google announced the existence of Cloud Pub/Sub, a managed service on the Google public cloud for sending and receiving data in “messages” — basically, middleware for applications. Today, Google is moving it out of alpha status, which requires people to fill out a form for access, and making it available for anyone to use in beta.

For now, while the service is in beta, it is free, according to a blog post today from product manager Rohit Khare.

Once it’s generally available to all to use, the service will cost 40 cents per million operations of the Cloud Pub/Sub application programming interface (API) operations for the first 100 million operations. After that point, the price drops to 25 cents per million for the next 2.4 billion operations. And after that, the price goes even lower, to 5 cents per million.

Of course, data storage and movement of data from one Google data center to another will cost money, as always.

The beta availability of the tool makes Google more friendly to developers looking to easily build complex, data-rich applications. And that’s important as Amazon Web Services continues to lead the public cloud market, with Microsoft also playing a key role alongside Google.

Open-source publish-subscribe messaging tools do exist. Apache Kafka is probably the most prominent one. But it takes time to implement Kafka yourself. So this tool could come in handy for certain programmers.

Cloud Pub/Sub does have quotas. For instance, requests for publishing data — and individual messages — are capped at 10MB. See the full list of quotas for more detail.