In our definition a hidden backlink is a backlink from a website which blocks common backlink monitoring tools from crawling their website but not search engines. Due to technical limitations we don't validate whether a site lets search engines crawl it or not. We will fix this issue with an indexing checker soon.
Because a hidden backlink passes link juice like any other backlink. There is no difference from a search engine perspective. If you just monitor visible backlinks you're most likely missing a part. How big the influence of hidden backlinks are, depends heavily on each website. Even if a website doesn't have hidden backlinks, it's always good to know.
We won't go into detail here. The most widespread methods for hiding outgoing links from link metric crawlers use robots.txt disallow entries, server settings (.htaccess for e.g.) or HTML cloaking. These methods are supported of course. More sophisticated methods or details won't be disclosed. We put a lot of effort into finding new methods in order to support them.
In general precision of our data is determined by detection rate and crawling reach. By the time Linxact gets more popular, the demand for bypassing our detection algorithm rises. It's a typical cats-and-mouse game but we're prepared to spend a lot of money and work into research and development. So to answer the question we are currently in a good state regarding our detection rate. It can be improved of course but nothing major is missing at this stage.
The other factor determing precision of our data is crawling reach. The more URLs we are able to crawl the better our dataset looms reality. Currently we are able to monitor URLs of 2.2 billion different active hosts. This number decreases after several quality filters have been applied (e.g. spam removal, removal of parked domains etc.) though. This is of course far away from the crawling reach of bigger companies but still more than the estimated number of active hosts of 1.8 billion given by internetlivestats.com.
But as every early stage startup we have to keep costs as low as possible at the beginning. Therefore we filter asian websites out at the current stage since most customers won't be interested in hidden backlinks from such websites anyways.
Since Linxact is quite new, historic datasets and the needed functionality don't exist yet. We will look into supporting historic hidden backlink data in the future but that's nothing we are focusing on right now.
No but there is always the possibility to export all hidden backlinks in order to analyze them with a SEO metrics bulk checker.
We don't focus on SEO metrics. There are enough companies with much more expertise in this regard. Instead we aim for a maximum of data integrity. Since we only offer hidden backlink data, it's essential to have a subscription of a common link metric tool in addition to our service anyways.
Private Blog Networks (short PBNs) are widely used for the only purpose to rank websites higher on search engines. All domains of a PBN are owned and in control of one entity. To get the most gain out of a PBN, it's nearby to block third party backlink monitoring tools to hide crucial link profile information from competitors. Private Blog Networks have gained much popularity in the SEO industry the last few years because of it's effectiveness.
This remains to be disclosed but we can guarentee you that we're steadily improving Linxact. When we feel comfortable with features, reliability and data precision we can offer we will mark it as final.