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Need to send files locally with context? Synclan blends LAN transfers with an IM chat feed

#opensource #selfhosted #privacy #tauri

🚀 Synclan: A LAN File Transfer Tool with a Feishu/Lark-like IM Experience

TL;DR: An open-source, local area network (LAN) instant messaging & file transfer tool that requires no internet, no third-party cloud servers, and no app installation on recipient devices. Just launch the desktop app, and any other device (phone, laptop, tablet) can scan a QR code to chat, share files, and send rich text/Markdown.

Synclan Home

🎯 Why Build Synclan?

We frequently face the need to transfer files between devices locally:

  • Quickly sharing files, code snippets, or screenshots between work PCs.
  • Sharing photos between personal computers at home.
  • Sending a temporary document to a colleague's laptop without adding them on social media.
  • Transferring sensitive documents without routing through external cloud servers.

While excellent LAN tools like LocalSend and AirDrop exist, high-frequency usage reveals two pain points:

  1. Transaction-based, not Context-based Tools like LocalSend focus on Select File ➔ Send ➔ Receive. However, real-world collaboration often requires continuous communication: sending a quick note explaining the file, sharing follow-up links, or referencing previously sent history—a workflow much closer to an Instant Messaging (IM) app.
  2. Installation Barriers Installing a dedicated app on every guest or temporary device isn't always practical or permitted.

Goal: "Launch the app, discover local devices, and exchange files & messages naturally like an IM chat."

Inspired by the polished user experience of modern team chat apps like Feishu/Lark, Synclan blends IM rich-text editing, hotkeys, and media integration into local-network communication.

⚡ Comparison with Popular Tools

Feature WeChat / Lark AirDrop LocalSend Synclan
Network Mechanism Cloud Servers LAN / Bluetooth LAN 100% Pure LAN
Interaction Model IM Chat Feed Pop-up Alert Receive Card IM Chat Feed
Recipient Requirement Client App Required Apple Devices Only Client App Required No App (Browser QR Scan)
Uncompressed Media ❌ (Compressed/Limited) ✅ ✅ ✅ (Original Quality)

🛠️ System Architecture & Tech Stack

Synclan utilizes a hybrid server/web architecture: The desktop app acts as the host/server, allowing web browsers on other devices to connect zero-install.

+-----------------------------------------------------------+
|                    Synclan Desktop App                    |
|                                                           |
|  +--------------------+   +----------------------------+  |
|  |   Tauri 2.0 (GUI)  |   |   Rust Core (Backend)      |  |
|  +--------------------+   |  - Axum (HTTP / File)      |  |
|                           |  - Socket.IO (Real-time)   |  |
|                           |  - SQLite (Local DB)       |  |
|                           +----------------------------+  |
+-----------------------------------------------------------+
                                ▲
                                │ LAN (HTTP / WebSockets)
                        +-------┴-------+
                        │               │
                 +--------------+  +---------------+
                 |  Mobile Web  |  |  PC Browser   |
                 +--------------+  +---------------+
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Core Technologies

  • Frontend: React, TypeScript, Tailwind CSS, Shadcn/ui.
  • Desktop Shell: Tauri 2.0 (offering minimal memory footprint compared to Electron).
  • Backend: Rust (Axum for HTTP API & Static Web Serving, Socket.IO for real-time signaling, SQLx + SQLite for local storage).

✨ Key Features

1. Rich Text Input Powered by Lexical

Supports rich text formatting, Markdown shortcuts, Emojis, code block highlighting, image pasting from clipboard, and file drag-and-drop directly into the composer.

Synclan

Synclan

Synclan

2. Large File Chunked Uploads

Files remain strictly within your local network. Large files are automatically split into chunked streams (Chunks ➔ Server Stream ➔ Reassembly), preventing network dropouts from ruining long transfers while keeping RAM usage minimal.

3. QR Code & Web Access

Automated local IP binding and QR code generation. Any smartphone or desktop browser can instantly join the session by pointing their camera at the screen—no registration or account setup needed.

Synclan

Synclan

Synclan

4. Data Security & Open API

All data is saved locally in an encrypted SQLite database. Includes support for HTTPS and self-signed certificates. An OpenAPI UI is built-in out of the box (http://127.0.0.1:53317/api/docs) for easy custom integrations.

Synclan

🗺️ Roadmap

  • [ ] File transfer resume (pause/continue) & granular progress details
  • [ ] Richer message types (voice notes, collapsible code previews)
  • [ ] Granular device access permissions & PIN verification
  • [ ] Enhanced local TLS/HTTPS cert management
  • [ ] Further optimizations for mobile browsers

📝 Wrap Up

Building Synclan has been a fun journey combining React, Tauri, Rust, WebSocket signaling, chunked file pipelines, and rich text editors into a practical, everyday solution.

If you frequently transfer files across different OS platforms in your home or office network, give it a spin!

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