HexFiend is a native macOS hex editor designed for opening and editing binary files of any size without loading them entirely into memory. It uses a 64-bit addressable data model with memory-mapped file access, enabling navigation of multi-gigabyte files while maintaining byte-level undo for insert and delete operations.
The editor distinguishes itself through a diff algorithm for binary file comparison that accounts for insertions and deletions, and a template-based structure parsing system that uses user-defined scripts to visualize binary file layouts. It also includes a typed data interpretation layer for inspecting raw bytes as integers, floats, and other types with configurable endianness and signedness.
Beyond its core editing capabilities, HexFiend provides fast search for byte patterns in large files and offers a permissively licensed framework for embedding hex views into other macOS applications. The project maintains a clean model-view-controller separation, allowing its binary data model to be reused across different applications.