Google Translate ajax API

I needed to check language and translate a lot of texts, so I wrote those 2 procs inspired from Google AJAX search API and getting all I needed from official page

I'm testing it right now, I made +5000 requests for lang_detect and around 1500 translations in one day, and google let me do ... (500 ms between each lang_detect and 1s between each translation).

g_translate string: Returns a string of text translated to english or -1 in case of error.

lang_detect string: Returns the detected language as a 2 chars string and a floating number between 1 and 0 representing confidence. In case of error, language is "error" and confidence is -1.

package require http
package require json
proc g_translate to_translate {
     set api_key {<your API key here>}
     set q [::http::formatQuery sig $api_key q $to_translate v 1.0 ]
     set url http://ajax.googleapis.com/ajax/services/language/translate?langpair=%7Cen
     set t [http::geturl $url -query $q]
     set translated {}
     if {[http::ncode $t] == 200} {
         set d [http::data $t]
         set idx 0
         while {$idx >= 0} {
             set idx [string first {responseData} $d $idx]
             if {$idx >= 0} {
                 set jd [json::json2dict [string range $d [expr {$idx-2}] end]]
                 if {[dict get $jd responseData] ne {null}} {
                     set translated [dict get $jd responseData translatedText]
                 }
                 incr idx 5
             }
         }
     } else {
       set translated -1
       puts Error=[http::error $t]
       puts Status=[http::status $t]
       puts Code=[http::code $t]
       puts Ncode=[http::ncode $t]
       puts Data=[http::data $t]
     }
     http::cleanup $t
     return $translated
}


proc lang_detect to_translate {
    set api_key {<your API key here>}
    set q [::http::formatQuery sig $api_key q $to_translate v 1.0 ]
    set url "http://ajax.googleapis.com/ajax/services/language/detect?"
    # works only with GET 
    append url $q
    set t [http::geturl $url]
    set translated {} 
    if {[http::ncode $t] == 200} {
      set d [http::data $t]
      set idx 0
      while {$idx >= 0} {
          set idx [string first {responseData} $d $idx]
          if {$idx >= 0} {
              set jd [json::json2dict [string range $d [expr {$idx-2}] end]]
              if {[dict get $jd responseData] ne {null}} {
               set lang [dict get $jd responseData language]
               set conf [dict get $jd responseData confidence]
              }
              incr idx 5
          }
      }
    } else {
      set lang error
      set conf -1
      puts Error=[http::error $t]
      puts Status=[http::status $t]
      puts Code=[http::code $t]
      puts Ncode=[http::ncode $t]
    }
    http::cleanup $t
    return "$lang $conf"
}