Marquez is an open source metadata server that acts as a central hub for data lineage across organizations. WeWork released it as the reference implementation of OpenLineage, meaning it's the official standard everyone builds against. The core job is straightforward: collect metadata from your data pipelines, store it, and make it queryable so you can actually understand what's happening in your data ecosystem. This matters for three concrete reasons — data governance (knowing who owns what), quality monitoring (catching problems before they cascade), and performance analytics (finding bottlenecks). The platform works with major orchestration and processing tools already. If you're running Apache Airflow, Spark, Flink, dbt, or Dagster, Marquez has integrations ready to go. It exposes a real-time endpoint that accepts OpenLineage-formatted metadata from your running jobs, so you don't need custom connectors for every tool. The web UI gives you a visual graph of your entire data ecosystem — you can see which datasets feed into which jobs, trace a single dataset's path through multiple pipelines, and dig into execution details and metrics without leaving the interface. Beyond the UI, Marquez exposes a lineage API for automation. This is where it gets practical. You can query the dependency tree programmatically to automate backfills (rerunning historical data), investigate root causes when something breaks, or enrich your existing data catalogs and quality systems with lineage context. The API lets you traverse dependencies across different orchestration platforms, which matters because most organizations don't use just one tool — they have Airflow here, Spark there, dbt somewhere else.