Splunk named itself after spelunking, because digging through machine logs felt like crawling through a cave with a flashlight. Every server, app and network device writes a running diary of what it does. Most companies ignored those files until something broke. Splunk made them searchable like a web page. When it filed to go public in early 2012, investors were hungry for anything labeled big data.

A Search Box for Logs

Michael Baum, Rob Das and Erik Swan founded Splunk in San Francisco in 2003. Their bet was that the plain text pouring out of machines held answers no one was reading. Splunk's software pulled in that text from any source and indexed it. An engineer could then type a search and find the error behind an outage in minutes. Security teams soon used the same tool to hunt for attackers.

A Double on Day One

Splunk priced its IPO at $17 a share on April 18, 2012, well above its first range of $11 to $13. The stock more than doubled on its first day of trading on Nasdaq. It was the best debut for a tech IPO since LinkedIn a year earlier. Splunk grew into a security and observability business sold to large companies. In March 2024 Cisco completed its purchase of Splunk for about $28 billion.

Cover: The Grotto of Egeria, Rome, Robert MacPherson. Art Institute of Chicago, public domain. Chosen for a cave (spelunking, the root of the name).