Zillow API asking for CAPTCHA
<p>I've been using the GetSearchResults web service and it has suddenly stopped working because it's asking me to respond to a Captcha, which doesn't make any sense because it's an API so it shouldn't be asking for human response.</p>

<p>This code is running in Google App Engine. On localhost it works fine, but fails in production.</p>

<p>Below shows what my code is trying to fetch. The is HTML that is coming contains a Captcha. I should be getting XML back instead. What's going on?</p>

<pre><code>zillow: http://www.zillow.com/webservice/GetSearchResults.htm?zws-id=[API KEY REMOVED]&amp;address=10797+Alameda+Ave&amp;citystatezip=92316&amp;rentzestimate=1
zillow results: 

&lt;html&gt;&lt;head&gt;&lt;title&gt;Zillow: Real Estate, Apartments, Mortgage &amp;amp; Home Values in the US&lt;/title&gt;&lt;meta http-equiv="X-UA-Compatible" content="IE=8, IE=9"/&gt;&lt;meta name="ROBOTS" content="NOINDEX, NOFOLLOW"/&gt;&lt;link href="//fonts.googleapis.com/css?family=Open+Sans:400&amp;subset=latin" rel="stylesheet" type="text/css"/&gt;&lt;link href="http://www.zillowstatic.com/vstatic/5b67875/static/css/z-pages/captcha.css" type="text/css" rel="stylesheet" media="screen"/&gt;&lt;script language="javascript"&gt;
            function onReCaptchaLoad() {
                window.reCaptchaLoaded = true;
            }

            window.setTimeout(function () {
                if (!window.reCaptchaLoaded) {
                   document.getElementById('norecaptcha').value = true;
                   document.getElementById('captcha-form').submit();
                }
            }, 5000);
        &lt;/script&gt;&lt;/head&gt;&lt;body&gt;&lt;main class="zsg-layout-content"&gt;&lt;div class="error-content-block"&gt;&lt;div class="error-text-content"&gt;&lt;!-- &lt;h1&gt;Captcha&lt;/h1&gt; --&gt;&lt;h5&gt;Please verify you're a human to continue.&lt;/h5&gt;&lt;div id="content" class="captcha-container"&gt;&lt;form method="POST" action="" id="captcha-form"&gt;&lt;script type="text/javascript"&gt;
var RecaptchaOptions = {"theme":"white","lang":"en-US"};
&lt;/script&gt;
&lt;script type="text/javascript" src="http://www.google.com/recaptcha/api.js" async defer onload="onReCaptchaLoad()"&gt;&lt;/script&gt;
&lt;div class="g-recaptcha" data-sitekey="6Lf2nvMSAAAAAMQ5p6WlAfDEixMdOQgJsij-3_ud"&gt;&lt;/div&gt;&lt;br/&gt;&lt;input id="dest" name="dest" type="hidden" value="ognl:originalDestination"/&gt;&lt;input id="norecaptcha" name="norecaptcha" type="hidden" value="false"/&gt;&lt;button type="submit" class="zsg-button zsg-button_primary"&gt;Submit&lt;/button&gt;&lt;/form&gt;&lt;img src="http://www.zillowstatic.com/static/logos/logo-65x14.png" width="65" alt="Zillow" height="14"&gt;&lt;/img&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;/main&gt;&lt;/body&gt;&lt;/html&gt;&lt;!-- H:017  T:0ms  S:1554  R:Tue Dec 27 12:25:35 PST 2016  B:5.0.37586-master.3e1733a~hotfix_pre.27ccd5e --&gt;
</code></pre>