That's what the site author claimed he does. Others claim that what he actually does is just adding a few percentage points to the official stats[1]. Among academic economists, the site author is largely regarded as some kooky conspiracy theorist[2].

Personally I just see him more as small time business man making a nice living from satisfying some market demand for figures that proof government is lying to you. For those who want to find out for themselves, here's the raw BLS data[3] and methodology[4].

[1] https://azizonomics.com/2013/06/01/the-trouble-with-shadowst...

[2] https://www.thestreet.com/economonitor/emerging-markets/deco...

[3] https://www.bls.gov/developers/home.htm

[4] https://www.bls.gov/opub/hom/pdf/cpihom.pdf