There are some support for syntax highlighting for the following editors.
httest Buddy is a standalone httest IDE with embedded uptodate httest binaries for various plattforms.
Download htt.vim and filetype.vim from sourceforge. Create a .vim/syntax folder in your home directory if not allready exist. Place filetype.vim into .vim folder and htt.vim into .vim/syntax folder.
Note: If you have allready a filetype.vim in your .vim folder, you have to integrate the file endings ".htt" ".htb" into your _augroup filetypedetect_ as follow:
au BufNewFile,BufRead *.htt,*.htb setf htt
If you like to have command completion, which is available for vim7 add the following to your filetype.vim file
In insert mode you can type ctrl-x, ctrl-o and a pulldown will show you the httest commands.
There is a Xtext integration for Eclipse from Alain Stalder. Download htt-xtext-1.0.0.zip from sourceforge.