NeoForge is the official successor to Minecraft Forge, providing a comprehensive modding framework and API for Minecraft. It extends vanilla Minecraft through a patching system (coremods/ASM) and a rich event-driven architecture, allowing mods to hook into gameplay, rendering, networking, registries, capabilities (data attachments), and resource transfer. The repository includes the mod loader itself (client and server), a Gradle-based build system (buildSrc) for producing the framework and installer, and an extensive test framework (testframework/) with both unit and in-game game tests. The codebase is well-structured with clear client/server source splits, extensive use of codecs and data-driven JSON, and a modern transactional resource API for energy, fluids, and items. It is actively maintained with large community adoption.