Mullvad is a commercial VPN operated by Mullvad VPN AB in Gothenburg, Sweden (parent Amagicom AB). It encrypts device traffic and exits it from a shared IP on Mullvad's multi-region relay network so your ISP cannot see destinations and destination sites do not see your home IP. The service launched in 2009 and remains founder-owned, not a US-group or private-equity consumer VPN brand.
It exists for people who treat identity linkage as the purchase filter. Signup does not ask for an email, phone, or name. The app or website generates a random numbered account. That number plus remaining prepaid time is what you need to connect.
The concrete differentiator is that numbered-account model, with optional cash-by-post or self-hosted cryptocurrency payments if you also want to avoid card processors. Official desktop and mobile clients are published under GPL-3, and the company publishes a per-relay ownership list on a RAM-only network.