New Relic One` provides a platform for building and deploying custom apps to gain unique insights into data generated by various applications and systems. The company shares some of its popular open-source apps, including `Observability Maps`, `Metric Aggregator`, and `Workload Geo Ops`, which can be accessed through the `New Relic One Catalog`. These apps allow users to create customized views of their environment, aggregate metrics, and link workloads to physical locations. To deploy these apps, users need access to `New Relic One`, the `CLI`, a personal API key, and Node v10 or higher. The company also offers resources for building custom applications, including documentation, a developer toolkit, and a GraphQL explorer. Additionally, New Relic welcomes open-source contributions to its projects.