There are hundreds of third party PageRank tools that show Google's Toolbar PageRank score. Some of the more popular ones can be found by doing a search in Google for pagerank checker.
Many of these tools are now not able to produce an actual PageRank score for a site. This even goes for my PageRank prediction tool that was designed as an April Fools Joke in 2004.
Did Google intentionally break what was working for third party application to check PageRank? Was it an accident? Is something broken at Google?
It does not appear to be an issue with every tool. But it is impacting many tools.
How does one get the PageRank toolbar score? More on that with these articles:
- New Toolbar and New PageRank Checksum Algorithm - PageRank Checksum Algorithm Cracked (Again) - Tools to Check a Sites True Google Toolbar PageRank Score
Forum discussion at DigitalPoint Forums.

Comments:
Dave
11/11/2007 12:46 am
Plenty of them still are not working. Its a bit of pain in the old rearend.
Matt Ellsworth
11/12/2007 12:10 pm
searchstatus for firefox still works fine - and thats the one i use a lot... but i'll be on the look out now for other tools not working.
Tiger
11/12/2007 01:45 pm
I think Google has blocked pagerank checker scripts for many web hosting providers like Ovh since last week (Thursday).
Resist
03/10/2008 10:18 am
Tiger is right, if you use a good proxy list it will still work fine.
Broken
11/12/2010 11:45 pm
I think google did this intentionally but I also think the 3rd parties will release updates shortly to bypass the block and allow us to view PR's within the SERP's again. PS. Matt, searchstatus only shows PageRanks within the actual site itself. I think the writer is talking about PageRank tools like seoquake, linkextend, seo site tools, etc that check the PageRanks within google searches
Broken
11/12/2010 11:46 pm
I just saw the post date for this was back in 2007... Has anyone had problems with viewing PageRanks in google searches the past few days using 3rd party PageRank checking tools?