Apache Airflow
Open-source platform for scheduling and monitoring data workflows
Free
Automation
Workflows are Python files that define tasks and dependencies. A web interface shows runs, logs, and failures. Hosted versions exist from cloud providers and Astronomer.
Airflow handles orchestration, not the data processing itself. It takes effort to run well at scale.
Prefect and Dagster are newer alternatives. Airflow suits data engineers who orchestrate batch pipelines.