Senddfile
EN

About Senddfile

Senddfile is a peer-to-peer (P2P) file transfer tool. The file goes straight from the sender's browser to the receiver's browser — without touching any server of ours.

How it works, technically

P2P transfers on the web use WebRTC, a standard technology built into modern browsers. For two browsers to connect, they first need to exchange some network information — address, connection configuration, route candidates. This exchange is called signaling.

On Senddfile, signaling happens via Firebase Firestore: each transfer creates a temporary document with this connection info. Once both sides are connected, that document is no longer needed.

The file contents are never sent to Firestore or to any server of ours. They flow exclusively through the direct channel between the two browsers.

What we see (and what we don't)

During signaling, the following data passes through our Firestore:

  • WebRTC connection metadata (SDP and ICE candidates) — these say nothing about the file contents, only how the browsers should connect.
  • The short transfer code (callId), used by the other side to find the session.

We have no access to the file, its name, its content, or to a history of what you transferred. We can't — that data never reaches our server. (We do measure anonymous, aggregated usage — see the privacy policy.)

The honest trade-off

Since nothing is stored, both sides have to be online at the same time during the transfer. If you close the tab, the transfer stops. That's a property of the model, not a bug: it's precisely because nothing sits on a server that your privacy is real.

How to use it

To send a file

  1. Open the transfers page and drop the file you want to send (or click to pick one).
  2. Senddfile shows a short code (and a QR code). Share it with whoever is receiving — copy, the share sheet, or scanning the QR.
  3. Keep the tab open. As soon as the other side joins, the transfer starts automatically.

To receive a file

  1. Open the transfers page and paste the code you were given (or scan the QR with your phone's camera to open the link).
  2. Start receiving, review the file's name and size, then click "Accept and save".
  3. Every browser receives the file in memory. When it finishes, Senddfile tries to start the download; your browser may use its configured folder or ask where to save it.

Frequently asked questions

Is it safe? Can you see my files?

No. The file content travels directly between the two browsers, encrypted by WebRTC. It never reaches our servers, so we can't see, store, or recover it.

Is there a file size limit?

Every web browser receives the file in memory. The preventive limit is 300 MiB on mobile and 1 GiB on desktop; it reduces memory pressure but does not measure free RAM or guarantee success. For larger files, use the future desktop app.

Which browsers work?

Any modern browser with WebRTC: Chrome, Edge, Firefox, Safari, and their mobile versions. The app tries to start the download when the file is complete; the browser decides whether to use its configured folder or ask where to save it.

Why does a transfer sometimes fail to connect?

Some restrictive networks (corporate, symmetric NAT) block direct connections. We only use public STUN for now, with no TURN relay. Switching networks, turning off a VPN, or trying mobile data usually helps.

Is it free? Is there a catch?

It's free. Because nothing is uploaded or stored, there are no hosting costs tied to your files — only the tiny, temporary signaling data that connects the two sides.

Contact

Questions, bug reports, or feedback? Reach out and we'll get back to you.

omtrix.contact@gmail.com