The .nmf file was a manifest that told naclwebplugin which .nexe to use for each architecture.
Today, the functionality once provided by naclwebplugin is handled by several modern technologies: naclwebplugin
The is primarily associated with Google’s Native Client (NaCl) technology. This sandboxing technique was designed to run compiled C and C++ code within a browser safely and at near-native speeds. While it was a major leap for web-based gaming and complex apps, Google officially deprecated NaCl in 2020 in favor of WebAssembly (Wasm) . naclwebplugin