spec

CloudEvents is a specification, not a piece of software. It defines a standard way to describe events so that different systems can send and receive them without each needing custom integration code. An event in this context is a signal that something happened: a file was uploaded, a payment was processed, a database record changed. The problem is that every platform describes these signals in its own format, so any team connecting two systems has to write translation logic. CloudEvents provides an agreed-upon format that any system can produce or consume.

The specification covers what fields an event must carry (such as a unique ID, the source that produced the event, the type of event, and the time it occurred) and how those fields should be packaged when sent over different transport protocols. Separate documents in the repository define bindings for HTTP, Kafka, MQTT, AMQP, NATS, and WebSockets, as well as serialization formats including JSON, Avro, and Protobuf. A team using HTTP and JSON can write to the same spec as a team using Kafka and Avro, and any middleware or tooling built around CloudEvents can handle both.

The project is hosted by the Cloud Native Computing Foundation, a well-regarded industry body that also oversees Kubernetes and other widely adopted infrastructure projects. CloudEvents graduated from that organization in January 2024, meaning it passed a maturity review and has broad real-world adoption. Major cloud providers and SaaS companies have backed the effort.

Alongside the spec documents, the repository links to official SDKs in a range of languages including Go, Java, Python, JavaScript, C#, Ruby, PHP, PowerShell, and Rust. These SDKs handle the mechanics of building and parsing CloudEvents so developers do not need to work with the raw specification documents.

If you are new to the project, the README recommends starting with the Primer document, which explains the goals and design thinking behind the spec before you read the technical details.