System1
Seattle, Washington, United States · Founded 2013
501-1000 employees · SST
Sourced & current · updated Oct 21, 2026Website
System1 is an American internet advertising company, formerly known as OpenMail, that operates a Responsive Acquisition Marketing Platform (RAMP) designed to connect advertisers with high-intent consumers while centering privacy as a core principle.
Where they sit
Stack tier: Ecosystem Services (A)
Customer Acquisition
A leading responsive acquisition marketing company with a vertically integrated model combining proprietary ad technology with a large owned-and-operated media portfolio
Ownership
Subsidiaries