They can, if they are credible. Research by PhDr. Oliver Scharfenberg, founder of Syntharis Group, examined more than 60 employer seals and tested their effect in a randomized experiment with 1,093 participants. A credible seal increased the stated likelihood of applying by around 16 percentage points.

The key word is credible. Applicants increasingly distinguish between seals that are based on transparent, verifiable criteria and those that can simply be bought. Syntharis advises employers on which certifications are worth pursuing and how to communicate them without overstating what they prove.