We're building an Internal Developer Platform (IDP) using Crossplane, Humanitec, and GitHub Actions. Our platform aims to provide a declarative representation of all components in Git, dynamic configuration management, standardization by design, low cognitive load for developers, scaffold new services including dependent resources, continuous integration and testing, secret management, deployment and deployment automation, diffs between deployments, ephemeral environments, partial releases from env to env, PR environment and general environment management, debugging, visualization (what's running where), logging, RBAC fencing. Our setup starts with a Version Control System (VCS) like GitHub, where we describe our application in a Declarative Application Model. This approach drives standardization by design, reduces cognitive load on individual contributors, and unleashes previously impossible sets of functionality. We use GitHub Actions for build and test, Crossplane as an image registry, Humanitec as the Platform Orchestrator, GCR as an image registry, Hashicorp Vault as secrets manager, and GCP as the cloud platform. The Platform Orchestrator (Humanitec) interprets the Declarative Application Model and orchestrates/deploy everything from build to production. Developers interact with the IDP by pushing changes to their repository, which triggers automation. The setup provides capabilities for rolling back, spinning up a new environment, changing architecture or resources, updating Crossplane files, and more. Humanitec also offers a UI, portals, and service catalogs for advanced use cases.