Firefly is a high-performance asynchronous networking framework for the JVM, written in Java and Kotlin. It provides a comprehensive set of I/O primitives including HTTP/1.1, HTTP/2, WebSocket (RFC 6455), TCP, and UDP, with both client and server implementations. The framework is designed around Kotlin coroutines and Java NIO2 (AIO), offering non-blocking, backpressure-aware streams and a router-based HTTP server with support for content negotiation, CORS, static file serving, and HTTP/2 upgrade. It also includes built-in SLF4J logging with XML configuration, a JSON serialization service, a WeChat enterprise bot module, and a JNI helper for native code integration. The codebase is modular (firefly-common, firefly-net, firefly-slf4j, firefly-serialization, firefly-wechat, firefly-example) and demonstrates deep protocol-level craftsmanship with custom HPACK, Huffman coding, and state-machine parsers. While primarily a library for building network services, it also serves as a reference implementation for protocol handling on the JVM.