glTF-Transform is a comprehensive SDK and CLI tool for processing, optimizing, and inspecting glTF/GLB 3D assets. It provides a rich property graph model (Document) for reading, editing, and writing glTF files, with full support for the glTF 2.0 specification and dozens of official extensions (KHR_materials_*, EXT_meshopt_compression, etc.). The library includes a broad set of transforms (compression, quantization, deduplication, welding, palette optimization, texture compression, etc.) that can be composed into custom pipelines. A command-line interface wraps all transforms for batch processing, and a viewer package provides real-time Three.js integration. Built as a monorepo with packages for core, extensions, functions, CLI, view, and docs, it demonstrates strong software engineering practices: property-graph architecture, extension system, observer patterns, and comprehensive unit/integration tests. Designed for both scripting in Node.js/Deno/Web and direct use from the command line.