The product that now sits inside tens of thousands of company networks began as a favour to a bank.
A Canadian bank had a Windows application and a problem: it needed sign-in that a phisher could not fool. The small team that would become Tailscale combined single sign-on with WireGuard, the lean modern VPN protocol, and handed it over. Avery Pennarun later described the result with a shrug. It worked so well for that 'one weird trick', he said in an interview, that they repackaged it for everyone.
The name came from a Google research paper, The Tail at Scale, and from the idea that most networking pain lives in the long tail of everyday cases.
Pennarun did not arrive at that moment by a straight road. He grew up in Thunder Bay, Ontario, where he first got online through a dial-up connection. At the University of Waterloo, where he earned a computer engineering degree in 2001, he co-founded Net Integration Technologies, a company built to make networking just work for small businesses. IBM bought it. Then came more than seven years at Google, working on Google Wallet and Google Fiber, where the networks were enormous and the people who kept them running were few.
He carried one irritation out of that world. Connecting two computers safely was still harder than it should be. In 2019, he started Tailscale with fellow Waterloo engineer David Carney, David Crawshaw and Brad Fitzpatrick, all of whom had worked at Google. The name came from a Google research paper, The Tail at Scale, and from the idea that most networking pain lives in the long tail of everyday cases.
Money followed the idea. Accel led a US$12m Series A in November 2020. Remote work during the pandemic pushed monthly users up, and in May 2022 CRV and Insight Partners led a US$100m round that valued the company near US$1bn, when it had only about 35 employees. Pennarun's tone in public stayed oddly small. He wrote that the company wanted to grow at a healthy pace, at human scale, and called the team a bunch of weirdos.
The hard part came after the fun part. A developer wants a tool that disappears. A security buyer wants controls, logs and policy. Pennarun has said the answer is to add only the enterprise features Tailscale truly needs and to keep the product small and coherent, never breaking what customers already rely on.
By 2025 a further US$160m Series C, again led by Accel, brought total funding to roughly US$272m, and the company counted more than 20,000 paying business customers. It does not publish revenue.
The lesson is in the origin story. The company did not start with a grand theory of the internet. It started with one customer who had one real problem, solved it, and noticed that everyone else had the same problem too.