How do third party applications and PageRank checking websites check for the PageRank number? Does Google provide this rank number with an API or can I retrieve it by entering something into the search box? I would like to make a simple script to record my page rank and work with it as a variable and I prefer to use only Google as a source.
How to find Google PageRank without third party tools?
pagerank
After reading comments to my question and a lot of searching I found the answer. To retrieve Google Page Rank, a query against one of Google's sub-domain http://toolbarqueries.google.com can be done. This sub-domain is actually only one of the ways I have found it may be done. The basic query syntax is in this format:http://toolbarqueries.google.com/tbr?client=navclient-auto&ch=[HASH]features=Rank&q=info:[URL]&num=100&filter=0It returns the Google Page Rank number, but [HASH] and [URL] must be provided,  I have found several PHP, Python and Java functions to retrieve Page Rank from Google and generate this hashed query correctly. As result when done correctly, it still works at the date of me writing this answer and you will still get response directly from Google's server. For PHP, I found this code working and easiest to customize, I checked against several websites that I know very well and it gives me same response as third party Page Rank applications.I have also found several blogs and articles supporting evidence of Page Rank retirement, it really looks like it does not change its value over time and all the Page Rank values are frozen.