P2P Session Handoff Guide — Transfer Files Without Uploading | MiOffice

The Problem with Cloud-Based File Sharing

Every time you share a file through Google Drive, Dropbox, WeTransfer, or email, that file is uploaded to a third-party server. Someone else's computer stores your data. Someone else's infrastructure controls access to it. For personal photos, business contracts, medical records, legal documents, and source code, this creates unnecessary privacy exposure.

Cloud file sharing also has practical limitations. Email caps attachments at 25MB. WeTransfer's free tier limits files to 2GB with a 7-day expiration. Google Drive requires a Google account. Dropbox requires a Dropbox account. Every service has upload and download speed bottlenecks because data must travel: your device to their server, then their server to the recipient.

MiOffice's P2P Session Handoff eliminates all of these problems. Files transfer directly from browser to browser over an encrypted WebRTC connection. Zero server upload. Zero file size limits. Zero accounts needed. 100% private.

P2P vs Cloud-Based Transfer

How to Transfer Files with P2P Session Handoff

1. 1

   Open Session Handoff

   The sender opens the P2P Session Handoff page. A unique session link is generated automatically.

2. 2

   Share the Session Link

   Send the session link to the receiver via any messaging app, email, or even by showing the QR code on screen. This link is only used for the WebRTC handshake — no file data passes through it.

3. 3

   Receiver Opens the Link

   The receiver clicks the link in their browser. The two browsers establish a direct peer-to-peer connection using WebRTC. This takes 1–3 seconds on most networks.

4. 4

   Drop Files and Transfer

   The sender drags files into the session window. Transfer begins immediately — data streams directly to the receiver's browser. Progress bars show real-time status. The receiver downloads files as they arrive.

How WebRTC P2P Works Under the Hood

WebRTC (Web Real-Time Communication) is a browser-native protocol originally designed for video calls. MiOffice uses its data channel feature to transfer arbitrary files between browsers. Here is the simplified flow:

Signaling: When the sender creates a session, a small JSON message (SDP offer) describing the sender's network capabilities is sent to a lightweight signaling server. When the receiver opens the link, they generate an SDP answer. These messages are a few kilobytes of text — they contain no file data, only network routing information.

ICE Negotiation: Both browsers discover their network addresses (local, STUN-reflected, TURN-relayed) and exchange ICE candidates through the signaling server. The browsers test these candidates and establish the most direct route possible — ideally a direct connection with zero relay servers.

Data Transfer: Once connected, the WebRTC data channel streams file bytes directly between browsers using SCTP over DTLS over UDP. All data is encrypted by default. The signaling server is no longer involved. File integrity is verified using checksums.

When to Use P2P vs Cloud Sharing

Use Cases

Tips for Best Transfer Experience

• --Use a stable network connection. P2P transfer speed depends on both parties' upload and download bandwidth. WiFi is fine for most files; wired connections are better for multi-gigabyte transfers.
• --Both browsers must stay open. Closing either browser tab ends the session and any in-progress transfer. Keep both tabs open and active until the transfer completes.
• --Zip large file collections first. While P2P handles individual large files well, transferring hundreds of small files is more efficient as a single ZIP archive. Use MiOffice's ZIP Creator to bundle files before transfer.
• --Works across devices and networks. P2P Session Handoff works between any two devices with a modern browser — Mac to Windows, phone to laptop, home WiFi to office network. The WebRTC protocol handles NAT traversal automatically.

Privacy & Security

• --Zero server storage. No file data ever touches MiOffice servers. The signaling server exchanges only WebRTC connection metadata (a few KB of text). Your file bytes flow exclusively between the two browsers.
• --DTLS encryption. All data transferred over the WebRTC data channel is encrypted using DTLS (Datagram Transport Layer Security). This is not optional — it is enforced by the WebRTC specification.
• --Session links are one-time use. Each session creates a unique connection between two specific browsers. The link cannot be reused by a third party to intercept data.
• --No account, no tracking. MiOffice does not require an account to use P2P transfers. No file metadata, names, sizes, or transfer history is logged on our servers.