📨 FileDropper

Peer-to-peer file and clipboard transfer between two browsers on the same network — no server, no upload, no native app. Your data travels directly device-to-device over a WebRTC DataChannel, so it never leaves your LAN.

The whole thing is static HTML/CSS/JS, so it can be served straight from GitHub Pages.

How it works

WebRTC lets two browsers open a direct peer-to-peer connection. The only thing that normally needs a server is signaling — the initial exchange of connection descriptors (which carry encryption keys and network candidates and are therefore too large to type by hand). FileDropper offers two ways to get through that step:

Easy mode (default) — a short word code

1. Device A: click Create a connection → it shows a code like badger-having-toothache.
2. Device B: click Join a connection → type the code → Connect.

A free public PeerJS broker maps the code to the WebRTC handshake. Only the tiny handshake touches the broker — the files themselves flow directly peer-to-peer (over the LAN when both devices are on it). Needs internet to reach the broker for the initial connect.

Manual mode (fallback) — copy/paste, fully offline

No broker, no third party — works even with no internet. The trade-off is a long code, because it carries the entire handshake itself:

1. Device A: Create → Use a manual code → copy the invite code.
2. Device B: Join → Use a manual code → paste it → Generate reply code → copy the reply code.
3. Device A: paste the reply code → Connect.

Either way, once connected

• Drag & drop files (or pick them) to send them — chunked with backpressure so even large files transfer reliably.
• Send text with the text box.
• Paste (⌘/Ctrl-V) anywhere on the page to send clipboard text or images.

Received items appear with a Save link (files) or Copy button (text).

Running it

Locally

Just open index.html — or serve the folder:

python3 -m http.server 8000   # then visit http://localhost:8000

On GitHub Pages

1. Push to GitHub.
2. Repo Settings → Pages → Build and deployment → Source: Deploy from a branch, pick your branch and / (root).
3. Visit https://<user>.github.io/filedropper/ on both devices.

Notes & limitations

• Same LAN works out of the box. Browsers use local (mDNS) ICE candidates, so the two machines connect directly. The bundled Google STUN server only helps if the peers are on different networks; on an isolated LAN it's ignored.
• HTTPS is required for clipboard read/write and is provided by GitHub Pages automatically (and by localhost).
• Received files are assembled in memory before download, so extremely large files are bounded by available RAM. (Streaming to disk via the File System Access API is a possible future enhancement.)
• No build step. The PeerJS library is vendored at vendor/peerjs.min.js, so the page is self-contained — only the easy-mode broker (not the page) needs the network. Manual mode needs nothing external at all.
• The easy-mode broker is the free public PeerJS cloud server. To avoid any third party, you can run your own PeerServer and point Peer at it via the host/port/path options in app.js.
• Peer ids on the public broker are global, so codes are namespaced (filedropper-v1-…) and a clashing id is retried automatically.