I have tried tons of Search Engine Rank Checker Tools (especially Google Rank Checker) in the past to check my Keyword Ranking. But none of them actually worked for me. Of course, some of them did work but it’s good only to check the first 100 results or maybe 200 results in Google Search Engine Results Pages (SERPs). If a Google Position Checker claims that it checks the Top 1000 results then most probably the results are not accurate. And those tools usually show different numbers if we double check the results. So I would say don’t trust those sites.
If you still don’t believe me then try the following Free Google Rank Checker Tools. These are the top Google SERP Checker tools which I got for the queries related to SERP Checker and Keyword Ranking.