I offer a widget to my clients which when deployed on their webpage display pricing data. The widget is written in PHP and is deployed using an iframe as follows
<iframe id="widget" src="http://www.example.com/customers/widget.php"
style="width:290px;height:210px; border:none;" scrolling="no" frameborder="0">
</iframe>
Inside the widget, I have an anchor tag which links back to my website
Powered by <a href="http://www.example.com">example.com</a>
and I want this to be crawled by Googlebot etc so I could get an SERPS link from it.
A couple of my clients have deployed the widget but it doesn't look like the iframe content is crawled by Google. Essentially I'm not seeing a link back from these websites. The webpages where the widget is deployed are well ranked in google (PR 2,3) and have good domain authority - so I know thats not the issue.
Is there a better way to deploy the widget (instead of iframe) to make it crawlable by google?
Google will not count links inside iframes because your client's website is basically loading the content from your website (so it's counted as a link from your own website instead from that of your client). Ususally, the widget creator would provide a copy & paste ready snippet that an interested webmaster would take and insert in his website like this:
<iframe id="widget" src="http://www.example.com/customers/widget.php"
style="width:290px;height:210px; border:none;" scrolling="no" frameborder="0">
</iframe>
<p>Powered by <a href="http://www.example.com">example.com</a></p>
In your case, you would simply place the link to your page below the iframe, not in it.
That being said, I would strongly advise you to add a rel=nofollow to the "Powered by ..." link. Otherwise you're running the risk of getting your page penalized. From the Google guidelines:
Additionally, creating links that weren’t editorially placed or vouched for by the site’s owner on a page, otherwise known as unnatural links, can be considered a violation of our guidelines. Here are a few common examples of unnatural links that may violate our guidelines:
[...]
Keyword-rich, hidden or low-quality links embedded in widgets that are distributed across various sites, for example ...
Altough you're not using a "keyword rich anchor" in your example we have seen cases where widget links like these have been reported as problematic in the Google Webmaster Tools.