Note: The layout of the web UIs that are shown in the following examples are for Apache Spark 2.0.2. See The Spark web UI port number For more information about where to find the port numbers, see Configuring networking for Apache Spark. SPARK_MASTER_OPTS, Configuration properties that apply only to the master in the form '-Dx=y' (default: none). Spark Standalone Mode - Spark 3.0.1 Documentation, Port for the master web UI (default: 8080). If you are running an application in YARN cluster mode, the driver is located in the ApplicationMaster for the application on the cluster. The driver may be located on the cluster's master node if you run in YARN client mode. This includes: A list of This takes you to the application master's web UI at port 20888 wherever the driver is located. Every SparkContext launches a Web UI, by default on port 4040, that displays useful information about the application. Monitoring and Instrumentation, Web Interfaces.