dolphinscheduler

If you run data pipelines — ETL jobs, batch processing, scheduled reports — and need something to orchestrate when things run and in what order, DolphinScheduler handles that. Think of it as a visual workflow scheduler where you drag and drop tasks into a pipeline and it manages dependencies, retries, and scheduling.

It is an Apache project with 14K stars, backed by a real community. Supports tasks in Python, Shell, SQL, Spark, Flink, and more. The visual DAG editor makes it accessible to people who are not writing code for a living.

The catch: it is Java-based and the self-hosted setup is not trivial — you need ZooKeeper and a database. The UI is functional but dated compared to newer tools like Dagster or Prefect. And the documentation has rough patches, especially for non-Chinese-speaking users (the project originated in China).