DropZone — Instant LAN File Sharing

LAN file sharing where only the host needs to install anything. Everyone else just uses their browser — no app needed.

Description

Sharing files between phones and computers on the same WiFi should be simple. It isn't.

AirDrop works beautifully — but only if everyone has Apple hardware. Android apps like LocalSend and SHAREit are great — but everyone in the room has to download and install the same app before anything can happen. And getting a group of people to do that in the moment, especially across different devices and comfort levels, is friction.

DropZone takes a different approach: only the host installs anything. Everyone else uses the browser they already have.

The host starts DropZone on their phone or laptop. A QR code appears on screen. Anyone nearby scans it with their camera — the same way you'd scan a menu at a restaurant — and their browser opens a simple page where they can instantly download whatever the host has shared, or upload files of their own back to the group. No app store. No account. No "wait, what version are you on?" It works on any phone, any laptop, any operating system, as long as you're on the same WiFi.

The only requirement for guests: a browser. Which everyone already has.

Requirements

Python 3.6+ (zero extra packages — pure stdlib)

How It Works

• Host page → http://localhost:7070
• Remote page → http://your-ip:7070/remote (or scan the QR code)

Both pages have:

• Tap-to-pick file upload using the device's native file picker
• A live list of all shared files, grouped by user, with download buttons
• An editable display name (auto-assigned a friendly name on first visit)

Bulk downloads

Beyond the per-file download buttons, DropZone offers two bulk options so you don't have to tap each file one at a time:

• All n files (.zip) — appears in each user's section header (when that user has more than one file). Bundles just that user's files into a single ZIP named DropZone-<UserName>.zip.
• Download everything (.zip) — a bar in the "Available on Network" card that bundles everyone else's files into one ZIP named DropZone-all-files.zip, organized into a subfolder per user (e.g. Alice/, Bob/). Your own files are excluded, since they're already listed in your upload box at the top. The bar sits directly between other people's files (above it) and your own contribution (below it), so its position mirrors exactly what it collects.

Both archives de-duplicate clashing filenames automatically (notes.txt, notes (1).txt), and the "everything" archive gives same-named users distinct folders (Bob, Bob (2)).

In the network list, other users are sorted alphabetically and your own section is pinned to the bottom.

The host page also shows a QR code — scan it to open the Remote page instantly on any phone without typing a URL. The Remote page shows the same QR at the bottom, so anyone already in can invite others by passing their phone around.

Run It

From any Python-3 enabled terminal:

cd /your/script/directory/
python3 DropZone.py

Then open http://localhost:7070 in your browser. The QR code on that page points remote users straight to http://your-ip:7070/remote.

Host on Android

These instructions use Termux. Install it from GitHub or F-Droid.

Important: Termux and any Termux add-ons (like Termux:Widget) must all be installed from the same source — all from F-Droid, or all from GitHub. Mixing sources causes a signature mismatch error.

One-Time Setup

Optionally choose your repository mirror region:

termux-change-repo

Install Python:

pkg update && pkg install python

Grant storage permission:

termux-setup-storage

An Android system permissions dialog will appear. Then see Run It above.

Optional: One-Tap Home Screen Shortcut

Install Termux:Widget from the same source as Termux.

Enable "Appear on top" permission for Termux:

Android Settings → Apps → ⋮ Menu → Special Access → Appear on top → Enable for Termux

Create the shortcuts folder:

mkdir -p ~/.shortcuts
chmod 700 ~/.shortcuts

Create the launcher script using nano:

nano ~/.shortcuts/DropZone

Type the following inside nano:

#!/data/data/com.termux/files/usr/bin/bash
cd /your/script/directory/
python3 DropZone.py

Save: Ctrl+O → Enter, exit: Ctrl+X

Make it executable:

chmod +x ~/.shortcuts/DropZone

Add the widget: long-press your home screen → Widgets → Termux:Widget → drag it onto your screen. Tap DropZone to launch.

Performance & memory

DropZone is built to stay light on the host, even when a room shares a lot of data:

• Files live on disk, not in RAM. Uploads are written to a temp folder; only small metadata (name, size, path) is kept in memory. Sharing many gigabytes does not hold gigabytes of RAM.
• Bounded-memory transfers. Downloads and ZIP bundles up to STREAM_THRESHOLD (default 64 MB) are buffered in memory so the browser gets an exact size and progress bar. Anything larger is streamed straight from disk (single files) or built to a temp ZIP and streamed (bundles), so peak memory stays flat regardless of total size.
• Multi-threaded with a backstop. Each request is handled in its own thread so one big download never freezes the room. MAX_CONCURRENT_TRANSFERS (default 4) caps how many heavy transfers run at once; shared state is guarded by a lock. Set THREADED = False near the top of DropZone.py to force single-threaded serving.
• Big-download warning. Before a bulk ZIP larger than WARN_THRESHOLD (default 512 MB), the page runs a quick speed probe against the host and asks for confirmation, showing the total size and a rough transfer-time estimate so whoever clicks knows what they're starting.

All four limits are plain constants near the top of DropZone.py and can be tuned to the host's hardware.

Notes

• Uploaded files are stored in a system temp folder while the server runs
• Temp files are automatically deleted when you stop the server with Ctrl+C
• State is in-memory — restarting the server clears the shared file lists
• To change the port, edit PORT = 7070 near the top of DropZone.py