NVRHI (NVIDIA Rendering Hardware Interface) is a C++ library that provides a unified hardware abstraction layer over Direct3D 11, Direct3D 12, and Vulkan 1.3. It is designed for high-performance rendering applications such as game engines and real-time visualization tools. The library exposes a consistent API for GPU resource management (textures, buffers, shaders, samplers), command list recording, pipeline execution (graphics, compute, meshlet, ray tracing), and automatic state tracking with barrier placement. It also includes a validation layer for debugging and correctness checks, and integrates NVIDIA-specific extensions like NVAPI, Aftermath crash dump analysis, and RTXMU memory utility. The architecture is backend-agnostic: common abstractions (resource lifecycle, state tracking, binding layouts) are implemented once and specialized for each backend. Key patterns include reference-counted resource handles (RefCountPtr), automatic barrier insertion based on resource state transitions, a two-phase binding system (BindingLayout → BindingSet), and upload/scratch buffer suballocation with version tracking. The library is distributed as a reusable SDK with CMake build support, shared-library exports, and optional feature toggles for NVAPI, Aftermath, RTXMU, and validation. While primarily an application library, NVRHI includes research-oriented features such as cooperative vector (CoopVec) support for AI/ML workloads, ray tracing acceleration structures (BLAS/TLAS, OMM, LSS), and cluster acceleration structure operations. These components are integrated into the same rendering pipeline abstraction, making the library suitable for both production graphics and experimental compute tasks.