Fpart is a filesystem partitioner (CLI tool in C) that splits file trees into balanced subsets called 'partitions' based on size, file count, or number of partitions. It uses a bin-packing algorithm to optimize space utilization and supports a live mode that generates partitions during filesystem crawling, with hooks to trigger immediate actions (e.g., rsync transfers). The companion tool fpsync (a POSIX shell script) wraps fpart and rsync/cpio/pax/tar to parallelize data migrations across local or SSH workers, providing job queue management, resume/replay, and progress reporting. The architecture is modular: fpart's C source is organized into separate modules for options, file entries, partitions, dispatch, and utilities, with an embedded FreeBSD fts(3) for filesystem traversal. Fpsync is a well-structured shell script that handles job scheduling, worker coordination, and run lifecycle. The project has been used by NASA, Amazon, Microsoft, and others for large-scale data migration.