LocalSend: The Open-Source Cross-Platform File Transfer Tool

You just took a screenshot on your phone and need it on your laptop—right now. Do you email it to yourself? Upload it to a cloud drive and wait? Fumble with a USB cable? If you've ever felt this pain, LocalSend is the tool you've been waiting for.

Table of Contents

• 1. What Is LocalSend?
• 2. Technical Architecture
• 3. Core Features
• 4. Deployment Guide
• 5. Comparison with Alternatives
• 6. Common Issues & Troubleshooting
• 7. FAQ
• 8. Who Should Use This?
• Verdict

---

1. What Is LocalSend?

LocalSend is a free, open-source cross-platform file transfer tool—think AirDrop, but for every operating system. Its core value proposition is simple: no internet required, no account needed, no configuration—just open and use.

What problems does it solve?

• WeChat and QQ have file size limits that make large transfers impossible
• Cloud drives are slow to upload/download and often require paid memberships
• FTP/SFTP setups are complex and intimidating for non-technical users
• Bluetooth transfers are unreliable and painfully slow

Ideal use cases:

• Transferring photos and videos between phone and computer
• Sharing large files across different devices
• Fast transfers within a local network
• Quick, temporary file sharing

---

2. Technical Architecture

LocalSend is built with Flutter, achieving true cross-platform support from a single codebase.

Tech Stack

| Component | Technology |
|-----------|-----------|
| Framework | Flutter 3.10+ |
| Language | Dart |
| Network Protocol | HTTP + REST API |
| Service Discovery | mDNS (Multicast DNS) |
| Encryption | TLS/SSL |

Architecture Design

┌──────────────────┐
│   Flutter UI     │
└────────┬─────────┘
         │
┌────────▼─────────┐
│  Business Logic  │
└────────┬─────────┘
         │
┌────────▼─────────┐
│  Network Layer   │
└────────┬─────────┘
         │
┌────────▼─────────┐
│  Platform APIs   │
└──────────────────┘

Core Technical Highlights

1. Service Discovery (mDNS)

// Device broadcasts its own service
_multicastSocket.send(
  "_localsend._tcp.local",
  port: 53317
);

// Discover other devices on the local network

_discoveredDevices = await _mdnsClient

  .lookup(ResourceRecordType.ptr);

2. HTTP File Transfer

// Send a file
await _httpClient.post(
  "http://${target.ip}:${target.port}/send",
  body: {
    "files": fileInfo,
    "token": authToken
  }
);

3. Progress Monitoring

// Real-time progress updates
Stream<TransferProgress> progressStream = 
  _fileSender.onProgress.listen((progress) {
    updateUI(progress.percentage);
  });

The use of mDNS for service discovery is a key design decision—it allows devices to find each other without any central server, keeping the entire system fully decentralized and private. The REST API over HTTP ensures compatibility across all platforms without exotic protocol dependencies.

---

3. Core Features

3.1 Multi-Platform Support

| Platform | Version Requirement | Status |
|----------|-------------------|--------|
| Windows | 10+ | Stable |
| macOS | 10.15+ | Stable |
| Linux | Ubuntu 20.04+ | Stable |
| Android | 5.0+ | Stable |
| iOS | 12.0+ | Stable |
| Web | — | In Development |

3.2 File Transfer Capabilities

Supported file types: All file types (no restrictions)

Transfer limits:

• Single file maximum: Unlimited (constrained only by disk space)
• Batch transfer: Folder support included
• Concurrent transfers: Multiple files simultaneously

Transfer speeds:

• LAN: 50–100 MB/s (depending on network)
• 5GHz Wi-Fi: 3–5x faster than 2.4GHz
• Wired network: Can reach gigabit speeds

3.3 Security Features

Encryption:

• All transfers use TLS encryption
• Device pairing requires explicit confirmation
• Optional password protection
• No transfer history is recorded

Privacy protection:

• Collects zero user data
• Depends on no third-party servers
• Fully open-source code
• Self-auditable

---

4. Deployment Guide

Windows Installation

Method 1: Microsoft Store (Recommended)

# 1. Open Microsoft Store
2. Search for "LocalSend"
3. Click Install
4. Auto-updates enabled

Method 2: Direct Download

# 1. Visit GitHub Releases
https://github.com/localsend/localsend/releases

2. Download the .exe installer
LocalSend-1.13.0-windows-x86-64.exe

3. Double-click to install
4. Optional: Add to startup

Method 3: Portable Version

# 1. Download the zip package
2. Extract to any directory
3. Run LocalSend.exe
4. No installation needed — carry it on a USB drive

macOS Installation

Method 1: Homebrew

# Install Homebrew (if not already installed)
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Install LocalSend
brew install --cask localsend

Update
brew upgrade --cask localsend

Method 2: Direct Download

# 1. Download the .dmg file
2. Double-click to open
3. Drag to the Applications folder
4. On first launch, allow access in System Preferences > Security & Privacy

Linux Installation

Ubuntu/Debian:

# Add repository
wget -qO- https://raw.githubusercontent.com/localsend/localsend/main/install.sh | bash

Install
sudo apt install localsend

Or download the .deb package
wget https://github.com/localsend/localsend/releases/download/v1.13.0/localsend_1.13.0_linux_amd64.deb
sudo dpkg -i localsend_1.13.0_linux_amd64.deb

Flatpak:

# Install Flatpak
sudo apt install flatpak

Install LocalSend
flatpak install flathub org.localsend.localsend

Run
flatpak run org.localsend.localsend

AppImage:

# Download AppImage
wget https://github.com/localsend/localsend/releases/download/v1.13.0/LocalSend-1.13.0-linux-x86-64.AppImage

Add execute permission
chmod +x LocalSend-1.13.0-linux-x86-64.AppImage

Run
./LocalSend-1.13.0-linux-x86-64.AppImage

Android Installation

Method 1: Google Play

1. Open Google Play
2. Search for "LocalSend"
3. Install

Method 2: F-Droid

1. Install F-Droid
2. Add the LocalSend repository
3. Install

Method 3: Direct APK

# Download and install APK
adb install LocalSend-1.13.0-android.apk

iOS Installation

1. Open App Store
2. Search for "LocalSend"
3. Install

---

5. Comparison with Alternatives

LocalSend vs AirDrop

| Feature | LocalSend | AirDrop |
|---------|-----------|---------|
| Cross-platform | All platforms | Apple only |
| Open source | Yes | No |
| Requires network | Local network | Not required |
| Transfer speed | Fast | Fast |
| Privacy | High | High |

LocalSend vs WeChat/QQ

| Feature | LocalSend | WeChat/QQ |
|---------|-----------|-----------|
| File size | Unlimited | 2GB/1GB |
| Transfer speed | Extremely fast | Slow (via server) |
| Privacy | High | Low |
| Network required | LAN only | Internet required |
| Compression | Lossless | May compress |

LocalSend vs FTP

| Feature | LocalSend | FTP |
|---------|-----------|-----|
| Setup difficulty | Simple | Complex |
| Encryption | TLS | Optional |
| Cross-platform | All platforms | Requires client |
| User experience | Excellent | Average |
| Speed | Fast | Fast |

LocalSend vs Syncthing

| Feature | LocalSend | Syncthing |
|---------|-----------|-----------|
| Use case | Quick transfers | Continuous sync |
| Setup | Instant | Requires configuration |
| Internet transfer | No | Yes |
| Resource usage | Minimal | Moderate |
| Best for | Ad-hoc sharing | Ongoing sync |

---

6. Common Issues & Troubleshooting

Issue 1: Cannot discover devices

# Troubleshooting steps:

1. Check network connection

   - All devices on the same Wi-Fi/network

   - Can ping each other

2. Check firewall

   - Allow LocalSend through firewall

   - Open port 53317

3. Restart the app

   - Fully close

   - Reopen

4. Manual addition

   - Use IP address

   - Specify port (default: 53317)

Issue 2: Slow transfer speed

# Troubleshooting steps:

1. Check network quality

   iperf3 -c TARGET_IP

2. Check for bandwidth competition

   - Close other downloads

   - Check background apps

3. Check device performance

   - CPU usage

   - Disk I/O

   - Memory usage

Quick fix: Switch to 5GHz Wi-Fi or use a wired connection

Issue 3: Transfer fails mid-way

# Troubleshooting steps:

1. Check storage space

   - Ensure receiver has enough free space

2. Check file permissions

   - Verify read/write access

3. Check file integrity

   - Compare file sizes

   - MD5 checksum: md5sum filename

4. Retry the transfer

   - Delete the partial file

   - Resend from scratch

Issue 4: Firewall blocking on Windows

# Allow LocalSend through Windows Firewall
netsh advfirewall firewall add rule name="LocalSend" dir=in action=allow program="C:\Program Files\LocalSend\LocalSend.exe" enable=yes

Or via Control Panel:
Control Panel -> Windows Defender Firewall -> Allow an app through firewall -> LocalSend

Issue 5: Firewall blocking on Linux

# UFW
sudo ufw allow 53317/tcp

iptables
sudo iptables -A INPUT -p tcp --dport 53317 -j ACCEPT

Save rules
sudo ufw reload

---

7. FAQ

Q1: Does LocalSend work without Wi-Fi?

Yes, as long as devices are on the same local network. This includes Ethernet, shared hotspots, or even a direct Ethernet cable between two machines.

Q2: Is LocalSend safe for sensitive files?

Yes. All transfers are encrypted with TLS, no data passes through third-party servers, and the code is fully open-source for independent security audits.

Q3: Can I send files to multiple devices at once?

Yes. LocalSend supports sending to multiple recipients simultaneously, though for best performance, keep concurrent transfers under 5.

Q4: Does LocalSend compress files during transfer?

No. Files are transferred exactly as they are—no compression, no quality loss.

Q5: Why can't my device see other devices?

The most common causes are: devices not on the same network, firewall blocking port 53317, or mDNS being disabled on the router. Try manually adding the device by IP address.

Q6: Can I use LocalSend over the internet?

Not by default. LocalSend is designed for local network use. For internet transfers, you'd need a VPN or tunnel like Tailscale to put both devices on the same virtual network.

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8. Who Should Use This?

Ideal for:

• Anyone who frequently transfers files between personal devices
• Teams working in the same office or shared space
• Privacy-conscious users who avoid cloud services
• Developers and power users who want a no-frills, fast transfer tool
• Families sharing photos and videos across phones and computers

Not ideal for:

• Transferring files across different networks (use Syncthing or a cloud drive instead)
• Enterprise-scale file management with audit requirements
• Scenarios requiring remote/internet-based transfers
• Large-scale automated sync (Syncthing is better suited for this)

---

Verdict

LocalSend is a genuinely practical open-source tool that solves the cross-platform file transfer problem elegantly. It requires no complex configuration, no internet connection, and no accounts—just devices on the same local network. The Flutter-based architecture ensures consistent performance across all major platforms, and the TLS encryption provides peace of mind for sensitive files.

If you regularly find yourself transferring files between devices, LocalSend is absolutely worth trying. It's the rare tool that delivers exactly what it promises, with zero friction.

GitHub Repository: https://github.com/localsend/localsend