BlazeMQ

I built a message broker that speaks the Kafka wire protocol, so any Kafka client (librdkafka, kafka-python, kcat, etc.) works without code changes. The entire binary is 52KB. No JVM, no ZooKeeper, no third-party libraries — just C++20 with kqueue/epoll. Starts in <10ms, uses 0% CPU when idle. I built this because running Kafka locally for development is painful — gigabytes of RAM, slow startup, ZooKeeper/KRaft configuration. I just wanted something that accepts produce requests and gets out of the way. Technical details: - Single-threaded event loop (kqueue on macOS, epoll on Linux) - Memory-mapped log segments (1GB pre-allocated, sequential I/O) - Lock-free SPSC/MPSC ring buffers with cache-line alignment - Kafka protocol v0-v3 including flexible versions (ApiVersions, Metadata, Produce) - Auto-topic creation on first produce or metadata request The most interesting bug I hit: librdkafka sends ApiVersions v3, which uses Kafka's "flexible versions" encoding. But there's a special exception in the protocol — ApiVersions responses must NOT include header tagged_fields for backwards compatibility. One extra byte shifted every subsequent field, causing librdkafka to compute a ~34GB malloc that crashed immediately. Current limitations: no consumer groups, no replication, single-threaded, no auth. It's v0.1.0 — consume support is next. MIT licensed, runs on macOS (Apple Silicon + Intel) and Linux.