MetaCert browser add-on can be set to block pornographic content

A free browser add-on that flags up and can block webpages containing sexually explicit content has been developed.

The MetaSurf software works not only for sites listed in search results but also pages that have links to other websites hosting adult content - including links within social networking sites such as Facebook. This means it can block a link to content without blocking the entire site.

For example many Facebook users found pornographic images appeared unexpectedly in some of their news feeds. MetaSurf said the software would have protected users from accidentally accessing those images.

The software is able to distinguish between a webpage containing sexually explicit adult content and a web address hosting important information; for example about breast cancer.

Paul Walsh of MetaCert said: "No longer do all sites have to be uniformly blocked or unblocked, since responsible adults can choose whether or not to enter the password which will enable them to progress through to a labelled site.

"Whether a user follows such links remains entirely a matter of personal choice, but it's an informed choice."

Once the software has been downloaded, users can choose to block sites, with a password needed to gain access to explicit content. During a search, the software displays an adult entertainment warning next to a site.

So far the company has catalogued more than 405 million pages with sexually explicit content and said it is labelling a further million pages every three days. MetaSurf also blocks access when the URL is typed manually into the browser. The software is updated automatically with newly-labelled sites.

MetaCert is available only for Firefox at the moment. Add-ons for Internet Explorer, Chrome and Safari will be available soon.