Radare is a portable reversing framework that can...

Disassemble (and assemble for) many different architectures
Debug with local native and remote debuggers (gdb, rap, webui, r2pipe, winedbg, windbg)
Run on Linux, *BSD, Windows, OSX, Android, iOS, Solaris and Haiku
Perform forensics on filesystems and data carving
Be scripted in Python, Javascript, Go and more
Support collaborative analysis using the embedded webserver
Visualize data structures of several file types
Patch programs to uncover new features or fix vulnerabilities
Use powerful analysis capabilities to speed up reversing
Aid in software exploitation

r2 is a rewrite from scratch of radare in order to provide a set of libraries and tools to work with binary files.

Radare project started as a forensics tool, an scriptable commandline hexadecimal editor able to open disk files, but later support for analyzing binaries, disassembling code, debugging programs, attaching to remote gdb servers, ..