Prometheus Metrics for Express

express-prom-bundle is an Express.js middleware designed to integrate popular Prometheus metrics into an application with minimal configuration. It bundles essential metrics, notably `up` and `http_request_duration_seconds`, which can be configured as either a histogram or a summary and labeled with HTTP status codes, methods, and paths. The current stable version is 8.0.0, which requires Express.js v5 and `prom-client` v15 or higher. The library maintains a steady release cadence, incorporating dependabot updates and new features, with major versions typically aligning with peer dependency updates. A key differentiator is its focus on ease of use, providing a consolidated solution for common Express metric needs, as well as features like path normalization and custom label support. Its middleware order dependency allows for selective metric collection, and it explicitly supports both CommonJS and ESM environments, shipping with TypeScript type definitions.