Serverless Workflow is a CNCF specification for defining declarative workflows that orchestrate functions, services, and events. Rather than being a single engine, it is a vendor-neutral DSL, expressed in YAML or JSON, that describes states, transitions, event triggers, retries, timeouts, and compensation logic in a portable format.
The spec models workflows as a finite state machine with state types such as operation, event, switch, parallel, foreach, callback, and inject. Data flows between states using JSONPath or jq expressions, and functions can be invoked via REST, gRPC, GraphQL, OpenAPI, AsyncAPI, or CloudEvents. This lets authors express long-running, event-driven business processes without coupling them to a specific runtime.
Multiple runtimes implement the specification, including SonataFlow (formerly Kogito Serverless Workflow), Synapse, and Automatiko. The goal is the same portability story that OCI brought to container images: a workflow written against the spec can move between compatible engines on Kubernetes, Knative, or hosted FaaS platforms.