Mixpanel-node is a server-side SDK for Mixpanel analytics, providing event tracking, people and group profile management, and feature flag evaluation (local and remote). It includes an optional OpenFeature provider for standardized flag evaluation. The SDK is structured as an npm workspace with two packages: the core `mixpanel` library and `@mixpanel/openfeature-server-provider`. The codebase demonstrates solid engineering practices: clear module separation, comprehensive test coverage with vitest and nock, robust error handling, deprecation warnings, and service account authentication support. The feature flags subsystem includes custom json-logic operators for semver and datetime comparison, validated against cross-platform golden vectors. The OpenFeature provider correctly maps Mixpanel's fallback reasons to OpenFeature error codes. Dependencies are modern, and the project is actively maintained with automated CI/CD and release workflows.