FLESS Client

GTK4 application for connecting to VLESS VPN protocol using xray-core.

FLESS Client is a lightweight native Linux GUI for VLESS protocol connections. It parses VLESS URLs, generates xray configuration on the fly, and manages the xray-core subprocess — all through a simple GTK4 interface built with GJS (GNOME JavaScript).

Features

• VLESS URL parsing — supports REALITY, TLS, and plain connections
• Auto-configuration — generates xray JSON config from a single VLESS link
• Native GTK4 UI — lightweight, no Electron, no web views
• Local proxy ports — SOCKS5 (127.0.0.1:10800) and HTTP (127.0.0.1:10801)
• Process lifecycle — starts/stops xray-core, auto-cleans config on disconnect

Requirements

• Linux with GJS (GNOME JavaScript) — preinstalled on Ubuntu/GNOME
• xray-core — install via package manager or download

Check GJS:

gjs --version

Install xray-core:

# Debian / Ubuntu
sudo apt install xray-core

# Arch Linux
sudo pacman -S xray

# Or download from GitHub releases and place xray in your PATH

Quick start

git clone https://github.com/freeeakn/fless-client.git
cd fless-client
gjs fless-client.js

1. Paste a VLESS URL into the input field
2. Click Connect
3. Configure your browser or system to use the local proxy:
   • SOCKS5: 127.0.0.1:10800
   • HTTP: 127.0.0.1:10801
4. Click Disconnect to stop

VLESS URL format

vless://UUID@SERVER:PORT?type=xhttp&encryption=none&path=/PATH&host=HOST&mode=auto&security=reality&fp=chrome&pbk=PUBLIC_KEY&sni=SNI&sid=SID#REMARK

Query parameters

Parameter	Description	Values
type	Transport protocol	tcp, xhttp, ws
security	Encryption layer	none, tls, reality
encryption	Stream encryption	none
path	Request path	any string
host	Host header	any string
mode	XHTTP multiplexing mode	auto, packet-up, stream-one
pbk	REALITY public key	base64 string
sni	Server Name Indication	hostname
fp	TLS fingerprint	chrome, firefox, safari
sid	REALITY short ID	hex string
spx	REALITY spider X path	URL-encoded path

Project structure

fless-client/
├── fless-client.js            # Main application (GJS + GTK4, single file)
├── com.fless.Client.yaml      # Flatpak manifest (GNOME Platform 49)
├── com.fless.Client.desktop   # Desktop entry for application menu
├── com.fless.Client.svg       # Application icon
├── README.md                  # English README
├── README.ru.md               # Russian README
├── README.sr.md               # Serbian README
└── .gitignore

The app looks for xray-core at ./xray-bin/xray first (if you place it there), or falls back to /usr/bin/xray.

Flatpak

A Flatpak manifest is included. It bundles xray-core, so no host installation is needed:

# Build
flatpak-builder --force-clean build-dir com.fless.Client.yaml

# Build and install locally
flatpak-builder --user --install --force-clean build-dir com.fless.Client.yaml

# Run
flatpak run com.fless.Client

Note: If you get a rofiles-fuse error, add --disable-rofiles-fuse.

Architecture

The application is a single GJS script with three core functions:

• parseVLESSUrl(url) — parses a vless:// URL into a config object with full REALITY support
• generateXrayConfig(config, configPath) — writes a complete xray JSON config (inbounds, outbounds, routing) to disk
• connectVPN(config) / disconnectVPN() — spawns xray-core as a subprocess, monitors it, and cleans up on exit

License

MIT