Google's webmaster guidelines prohibit many widget links in their link schemes section:
Here are a few common examples of unnatural links that may violate our guidelines:
- Links with optimized anchor text in articles or press releases distributed on other sites. ...
- Keyword-rich, hidden or low-quality links embedded in widgets that are distributed across various sites. ...
Google has has a blog post more specifically about widget links: Official Google Webmaster Central Blog: A reminder about widget links:
Widgets can help website owners enrich the experience of their site and engage users. However, some widgets add links to a site that a webmaster did not editorially place and contain anchor text that the webmaster does not control. Because these links are not naturally placed, they're considered a violation of Google Webmaster Guidelines.
Widget link building will get your site penalized when:
- The links contain keyword rich anchor text. Using your brand name or domain name in the link could be OK.
- The links cannot be removed without by the person placing the widget in their page. Google has said that the person placing the widget needs the editorial control to remove any links. You cannot force the link with technological means nor with terms of service.
Google has suggested several times that the only way to really be safe is to
nofollow any links given out with widgets.
So is your link building strategy a good one? Either you get no benefit because you use nofollow on the links, or you take on risk of manual penalties by including branded links. Google still may penalize you for those, or Google may revise their guidelines to prohibit those as well.
I personally have used widget links without nofollow for 10+ years. My site uses my brand name only as anchor text. I got a manual action against my site for unnatural links. However, I replied to it explaining my widget program and showing that my links only use my brand name. The manual action was lifted after a couple very worrying months with no changes required for my site.