shellnoob is a toolkit to help you write shellcode.

convert shellcode between different formats and sources. Formats currently supported: asm, bin, hex, obj, exe, C, python, ruby, pretty, safeasm, completec, shellstorm. (All details in the "Formats description" section.)
interactive asm-to-opcode conversion (and viceversa) mode. This is useful when you cannot use specific bytes in the shellcode and you want to figure out if a specific assembly instruction will cause problems.
support for both ATT & Intel syntax. Check the --intel switch.
support for 32 and 64 bits (when playing on x86_64 machine). Check the --64 switch.
resolve syscall numbers, constants, and error numbers (now implemented for real! Smile).
portable and easily deployable (it only relies on gcc/as/objdump and python). And it just one self-contained python script!
in-place development: you run ShellNoob directly on the target architecture!
built-in support for Linux/x86, Linux/x86_64, Linux/ARM, FreeBSD/x86, FreeBSD/x86_64.
"*prepend breakpoint*" option. Check the -c switch.
read from stdin / write to stdout support (use "-" as filename)
uber cheap debugging: check the --to-strace and --to-gdb option!
Use ShellNoob as a Python module in your scripts! Check the "ShellNoob as a library" section.
Verbose mode shows the low-level steps of the conversion: useful to debug / understand / learn!
Extra plugins: binary patching made easy with the --file-patch, --vm-patch, --fork-nopper options! (all details below)