LANLink

Status: active development (v0.5.0-dev) — interfaces and protocol may still change.

LANLink is a local-network file transfer and communication system. Trusted devices pair, authenticate, and transfer files over a LAN, Wi-Fi network, or mobile hotspot — no cloud, no accounts.

• WebSocket is the authenticated control plane (auth, pairing, ping, messages).
• HTTP is the data plane (all file transfers).

Components

Component	What it is
lanlink	The unified, pure-Go terminal binary. Runs a receiver (lanlink receive), sends files (lanlink send), and discovers/auto-connects to receivers (lanlink scan). Has zero dependency on the web UI or mobile app.
lanlink-agent (./agent)	The same receiver plus the browser dashboard at /ui. The only build that embeds agent-web.
lanlink CLI (./cli)	The original terminal client, preserved; a thin wrapper over the shared client library.
Mobile app (mobile/)	Expo / React Native app for Android & iOS: QR + network-scan pairing, file upload queue with progress/speed/ETA.

The desktop core is intentionally a pure-Go terminal application; the web dashboard and the mobile app are optional UI layers on top of it.

Features

• Device pairing with rotating tokens, or tokenless auto-connect on trusted LANs
• LAN discovery: receivers advertise via mDNS (_lanlink._tcp); lanlink scan (desktop) and a network-scan screen (mobile) find them and connect with no token
• Parallel chunked uploads (CLI), native streaming uploads (mobile), resumable uploads
• A polished web dashboard: live transfers, paired clients, output-folder browser, network scan
• Pure-Go, cross-compiles to Linux / Windows / arm64 with no cgo

Quick start

Run a receiver

go run ./cmd/lanlink receive      # headless, terminal QR + progress
# or, with the web dashboard:
go run ./agent                    # then open http://127.0.0.1:8787/ui

Connect and send (desktop → desktop)

go run ./cmd/lanlink scan                         # discover + auto-connect (no token)
go run ./cmd/lanlink send 192.168.1.42:8787 ./big.zip

Or pair explicitly with a token shown by the receiver:

go run ./cmd/lanlink pair 192.168.1.42:8787 123456

Mobile

1. cd mobile && npm install && npx expo start
2. In the app: Scan agent QR code, Scan network (tokenless), or enter the address + token.
3. Send files from the Device tab; watch progress in the Transfers tab.

Build

go build -o bin/lanlink ./cmd/lanlink   # terminal binary (no agent-web)
go build -o bin/agent   ./agent         # dashboard build

Cross-platform release binaries (Linux + Windows, pure Go):

scripts/build-release.sh                # → release/lanlink-* and lanlink-agent-*

See docs/release.md for Windows executables and the Android APK / EAS path.

Configuration

.env in the project root (see .env.example):

Variable	Description	Default
LANLINK_PORT	HTTP/WS port	8787
LANLINK_HOST	Force the advertised LAN address (else auto-detected)	(auto)
LANLINK_RECEIVED_DIR	Output folder for received files	received
TRANSFER_CHUNK_SIZE	Upload chunk size (bytes)	65536
TRANSFER_MAX_IN_FLIGHT_CHUNKS	Parallel chunk uploads	16

Security note

lanlink scan / mobile "Scan network" use an open, tokenless endpoint (POST /pair/auto) so any device on the local network can connect without a token. This is a deliberate convenience for trusted LANs. To require tokens, run the receiver with lanlink receive --no-discovery (disables mDNS advertising) and pair via QR/token only. Dashboard filesystem and scan routes (/ui/fs/*, /ui/discovery/scan) are loopback-only and never exposed to the LAN.

Documentation

• docs/architecture.md — how the system is built (packages, data flow, the pure-Go core / UI split)
• docs/protocol.md — the HTTP, WebSocket, and discovery wire protocol
• docs/development.md — building, running, and testing each component
• docs/release.md — producing desktop executables and the Android APK
• docs/plan.md — the prototype-to-release implementation plan

Version

v0.5.0-dev · MIT License