FractalBits is an S3-compatible object storage system designed for high performance and low latency. Using our custom-built fractal ART metadata engine, it delivers up to 1 million 4K read IOPS for single bucket with p99 latency ~5ms, at significantly lower cost than AWS S3 Express One Zone. Unlike standard S3, FractalBits provides native atomic rename support for both objects and directories. We are happy to open source our API server implementation (which support both actix and axum framework) today and welcome any feedback!