Does Step Functions replace AWS Lambda?

No. Step Functions coordinates work; Lambda can perform individual tasks. Direct service integrations can replace functions whose only job is to call another AWS API.

Is a state machine application code?

Yes. It defines production control flow and should be versioned, reviewed, tested, observed, and deployed with the same discipline as other application source.

Can an event start a Step Functions workflow?

Yes. Services such as EventBridge and API Gateway can start workflows, and workflows can call services or publish events as part of an execution.

What is AWS Step Functions?

AWS Step Functions is a managed workflow service for building distributed applications, automating processes, orchestrating microservices, and coordinating data or machine-learning pipelines. A workflow is a state machine whose states define tasks and control flow.

How this topic fits

Workflows

Coordinate multi-step work with visible state, retries, timeouts, compensation, approvals, and long-running business processes.

State machines, states, and executions

A Step Functions workflow is defined in Amazon States Language. Each state performs work or controls the flow by choosing, waiting, running branches in parallel, iterating over items, succeeding, or failing.

Every run is an execution with its own input, state transitions, and outcome. That explicit history makes the control path visible and separates workflow state from the runtime of any individual Lambda function or service task.

Call Lambda, supported AWS service integrations, activities, or approved external endpoints to perform work.

Branch, wait, map, run in parallel, pass data, or end the execution with an explicit outcome.

Shows state transitions and outcomes so developers and operators can inspect the workflow path.

Choose the workflow type from the workload

Step Functions provides Standard and Express workflows with different duration, execution, delivery, history, and pricing characteristics. Do not choose only from expected volume; auditability, integration pattern, duplicate tolerance, and maximum execution time also matter.

Keep the choice documented with the business operation. A workflow type that fits a high-rate transformation may not fit a long-running approval process, even if both use the same task services.

Service integrations and callbacks

Step Functions can call AWS services directly through optimized or AWS SDK integrations, which can remove functions that only translate one API request into another. The workflow role must still receive the narrow permissions required for those calls.

Request-response tasks continue after an API response. Other supported patterns can wait for a job or a callback token. Callbacks are useful for human or external work, but require timeout, authentication, duplicate, cancellation, and recovery decisions.

Failure handling and data flow

Configure retries for known transient errors with bounded backoff, and use catches for errors that need an alternate path. Avoid retrying validation or authorization failures that cannot succeed without a change in input or policy.

Transform and pass only the data each state needs. Large or sensitive payloads can increase cost, exposure, and coupling; store durable documents in an appropriate data service and pass stable references through the workflow.

Go deeper with AWS

Read the primary AWS documentation behind the service definitions and architecture guidance in this guide.

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Next steps

Continue with the concepts that most directly shape this decision.

What are serverless workflows?

Learn when explicit workflow state improves retries, branching, parallel work, human approval, visibility, and recovery in distributed applications.