Splunk is a data platform for security and observability, widely used for SIEM, log analysis, and full-stack monitoring. Founded in 2003 by Michael Baum, Rob Das, and Erik Swan, Splunk pioneered searching and analyzing machine data at scale. Cisco completed its acquisition of Splunk for approximately $28 billion in March 2024, and Splunk now operates as part of Cisco's security business while continuing to run its platform and brand.