I strongly recommend against using the Chrome app linked in the parent post. It uses a simple MD5 hash to derive the site-specific password from the master pass

I strongly recommend against using the Chrome app linked in the parent post. It uses a simple MD5 hash to derive the site-specific password from the master password, making it much easier for a site to use a brute-force approach to get the master password from the site-specific password. In addition, it seems that the code retrieves effective_tld_names.dat from Mozilla's server every time a password is hashed. Apart from performance considerations, this file is retrieved over plain HTTP giving adversaries another potential attack vector (by tampering with the version of effective_tld_names.dat sent to the browser).