Tailscale develops a partially open-source software-defined mesh virtual private network (VPN) and a web-based management service.

[4][better source needed] Founded in 2019 by Google engineers Avery Pennarun, David Crawshaw, David Carney, and Brad Fitzpatrick,[6] the company secured funding of $12 million in a Series A round in November 2020 led by Accel with seed investors, Heavybit and Uncork Capital participating.

[7] In May 2022, the company became a unicorn, raising a $100 million Series B round, led by CRV and Insight Partners, with participation from existing investors.

[9] The open-source software acts in combination with the management service to establish peer-to-peer or relayed VPN communication with other clients using the WireGuard protocol.

[10][11] Tailscale can open direct connection to the peer using NAT traversal techniques such as STUN or request port forwarding via UPnP IGD, NAT-PMP or PCP.