NSF Certified
A third-party certification from NSF confirming a product's contents match its label and meet contaminant limits.
NSF Certified means a product has been tested and certified by NSF, an independent public-health testing organization, under its dietary-supplement standard. Certification confirms the label accurately reflects what's inside, that the product does not contain undeclared ingredients, and that it is made in a facility audited for good manufacturing practices.
Like other third-party marks, it is a quality and label-accuracy check, not a claim about how well the supplement works.