this tool help u to convert ur string from text to hex and to use it while coding shellcode in stack method usage:
python hex.py "evil"
output :
[+] Orginal String : evil
[+] Reverse String : live
[+] String Length : 4
[+] String in H3X : 6576696c
[+] Reverse H3X : 6c697665
[+] For shellcode :
==> push 0x6c697665 || live
[+] Done