Protocol Buffers - Google's data interchange format
Protocol Buffers is Google's data interchange format for serialization and marshalling of structured data. The project is built with C++ as a core component and includes implementations in multiple languages including Java, C#, Python, Ruby, PHP, Objective-C, and others. It can be built and deployed using CMake, Bazel, or language-specific build systems, with support for various platforms including Windows, Linux, and macOS. The project includes a protocol compiler (protoc) that generates code from .proto schema files, along with comprehensive conformance testing across all supported language implementations to ensure correctness and completeness.