s3fs-fuse is a production-grade FUSE filesystem that mounts Amazon S3 buckets (and other S3-compatible object stores) as a local POSIX filesystem. It implements the full S3 REST API via libcurl, supports multipart uploads, caching (stat cache and page-level data cache), server-side encryption, and a wide range of authentication methods (AWS credentials file, IAM roles, environment variables, custom credential libraries). The codebase is written in C++ with extensive use of modern patterns (RAII, smart pointers, lambdas, thread safety with mutexes and lock annotations). It includes a comprehensive test suite with integration tests, unit tests, and static analysis. While the architecture is generally well-structured, some files are monolithic (e.g., curl.cpp >3500 lines, s3fs.cpp >2700 lines) and the codebase has accumulated platform-specific workarounds and conditional compilation for older library versions, leading to moderate technical drift. The project is actively maintained with regular commits.