VLESS, Xray, sing-box and Hysteria 2: what powers modern VPN apps

We run three VPN apps — VPN Russia, VPN Ninja and FastTube VPN — and their store pages mention words like VLESS, Xray, sing-box and Hysteria 2. Users often ask what these mean and why an app would need more than one. Here is a plain-language tour.

Protocol or engine?

Two different things hide behind these names:

• ✦a protocol is the language a VPN client and server use to talk to each other;
• ✦an engine (or core) is the software on your device that speaks those protocols, manages connections and routes traffic.

An app picks an engine, and the engine supports a set of protocols.

VLESS

VLESS is a lightweight protocol from the V2Ray and Xray family. It deliberately does very little on its own: it identifies the user and carries traffic with minimal overhead, while encryption is provided by TLS underneath. Because it adds almost no extra work per packet, it is fast and gentle on battery — which matters on phones and on Apple TV.

Xray

Xray is an open-source core that grew out of the V2Ray project. It implements VLESS along with VMess, Trojan and Shadowsocks, and adds its own performance features on top of TLS. It is mature and widely deployed, which makes it a reliable choice.

sing-box

sing-box is a universal proxy platform written in Go. One engine supports many protocols — VLESS, Trojan, Shadowsocks, Hysteria 2, TUIC, WireGuard and more — with a single configuration format. In VPN Russia 4.1 we made sing-box the default connection core and kept Xray available as an alternative.

Hysteria 2

Hysteria 2 runs over QUIC, the UDP-based transport behind HTTP/3. It uses its own congestion control designed for networks that lose packets — crowded Wi-Fi, mobile connections on the move, long international routes. Where TCP-based connections slow down sharply on such networks, Hysteria 2 tends to keep its speed. VPN Ninja supports it alongside Xray and sing-box.

Why one app ships two engines

Networks are not alike. Hotel Wi-Fi, a mobile operator and a corporate firewall each treat traffic differently, and an engine that is perfect on one network can be slow on another. That is why VPN Russia lets you switch between sing-box and Xray, and FastTube VPN offers two engines with a built-in speed test: if a connection feels slow, one tap tries the other path instead of leaving you to troubleshoot.

What does not change

Whatever protocol or engine is in use, your traffic is encrypted between your device and our server, and our VPN apps do not log the traffic itself, the sites you visit or your DNS queries. The details for each app are in its privacy policy — for example, VPN Russia.