Avery Pennarun graduated from the University of Waterloo with a computer engineering degree in 2001. He co-founded Net Integration Technologies, which IBM later acquired, and then spent more than seven years at Google.
In 2019 he started Tailscale with David Carney, David Crawshaw and Brad Fitzpatrick. The first product solved one problem for a Canadian bank: sign-in for a Windows app that a phisher could not fool. It combined single sign-on with WireGuard.
Accel led a $12 million Series A in November 2020. CRV and Insight Partners led a $100 million Series B in May 2022 at a valuation of about $1 billion.
A $160 million Series C led by Accel followed in April 2025, bringing total funding to about $272 million. Tailscale had more than 20,000 paying business customers by 2025 and does not publish revenue.