Google Ad Manager is a digital ad server that is integrated directly with Google Ad Exchange. It lets publishers sell inventory programmatically, allowing GAM to act as both a supply-side platform (SSP) and an ad server.
Because the vast majority of GAM’s services are free, it is probably the most widely known and used ad server in the market.
While Indie Ads Manager and GAM are both ad servers, they do function differently. For example, Indie Ads Manager is an all-in-one ad serving platform that allows publishers to serve ads directly to their email newsletter.
Despite GAM being extremely well-known and popular, there are many reasons why it might not be a good fit for you -
GAM has a reputation for being a confusing and complicated system to learn
Google offers training courses and certifications that are often required just to grasp basic navigation on the platform
Their support is poor unless you’re one of their paying customers (which is very expensive)
All this often leads to publishers needing to bring in outside expertise from ad agencies or by hiring an ad ops person.
In addition, the majority of GAM’s revenue still comes from search, which means that the needs of publishers (especially niche pubs) are not on Google’s radar.