In the last article, I showed how to create a Bing Spell Check service in Azure. Once you have created this service, you can now pass text to a web service to perform spell checking.

Given a text sample, the service checks the spelling of each token in the sample. A token is a word or two word that should be a single word, such as "arti cle", which is a misspelling of the word "article".

It returns an array of unrecognized tokens, along with suggested replacements for these misspelled tokens.

URL and querystring arguments

The URL for the web service is

You can add some optional querystring parameters to this URL:

Set this to "proof" if you want to check for spelling, grammar, and punctuation errors
Set it to "spell" if you only want to check for spelling errors.

If you omit the "mode" querystring argument, it defaults to "proof".

Set this to the Market Code of the country/language/culture you want to test. This is in the format [Language Code]-[Country Code], such as "en-US" for United States English. A full list of Market Codes can be fond here.

The "Proof" mode supports only en-US,  es-ES, and pt-BR Market Codes.

If you omit the mkt argument, the service will guess the market based on the text. Therefore, it is a good idea to include this value, even though it is optional.

Below is an example of a URL with some querystring values set.


You have the option to submit either an HTTP POST or an HTTP GET request to the URL. We will discuss the differences below.

If you use the GET verb, you pass the text to check in the querystring, as in the following example:

With the GET method, the text is limited to 1,500 characters

If you use the POST verb, the text is passed in the body of the request, as in the following example:


With the POST method, you can send text up to 10,000 characters long.


If successful, the web service will return an HTTP 200 ("OK") response, along with the following data in JSON format in the body of the response:

_type: "SpellCheck"

An array of "flaggedTokens", representing spelling errors found

Each flaggedToken consists of the following information:

  • offset: The position of the offending token within the text
  • token: The token text
  • type: The reason this token is in this list (usually "UnknownToken")
  • suggestion: An array of suggested replacements for the offending token. Each suggestion consists of the following:
  • score: a value (0-1) indicating the likelihood that this suggestion is the appropriate replacement

Below is an example of a response:

   "_type": "SpellCheck",
   "flaggedTokens": [{
     "offset": 5,
     "token": "ig",
     "type": "UnknownToken",
     "suggestions": [{
       "suggestion": "is",
       "score": 0.8922398888897022
   }, {
     "offset": 8,
     "token": "buuutifull",
     "type": "UnknownToken",
     "suggestions": [{
       "suggestion": "beautiful",
       "score": 0.8922398888897022
   }, {
     "offset": 27,
     "token": "tyme",
     "type": "UnknownToken",
     "suggestions": [{
       "suggestion": "time",
       "score": 0.8922398888897022

In this article, I showed how to call the Bing Spell Check service with either a GET or POST HTTP request.