Peer-to-peer file transfer explained
Browser peer-to-peer transfer commonly uses a WebRTC data channel. The browsers negotiate a route through a signaling service, try direct connectivity, and may use a TURN relay when networks prevent a direct path.
By PixoPublished
Signaling introduces the peers
Before a data channel opens, browsers exchange session descriptions and network candidates through a signaling mechanism. WebRTC does not prescribe a single signaling protocol. A service can coordinate the handshake without receiving the transferred file.
ICE searches for a working route
Interactive Connectivity Establishment gathers possible connection candidates and tests them. STUN can help a browser discover a public-facing address. Firewalls, carrier networks, and corporate policies can still prevent direct connectivity.
TURN is a relay, not necessarily storage
When a direct route cannot be established, a TURN server relays the packets. The relay sees network metadata needed to forward traffic, while WebRTC protects data-channel contents in transit. Whether an application adds storage is a separate product decision.
Chunking, backpressure, and integrity matter
Large files should be divided into bounded chunks so the sender does not overwhelm browser memory or the data channel. Applications need backpressure, recovery behavior, and an end-to-end digest to distinguish a complete verified file from a partial transfer.
Privacy depends on the selected mode
A direct connection may expose network candidates to the other peer. A relay-only option can hide the direct address from that peer at the cost of routing traffic through infrastructure. Neither mode verifies a human identity unless the product adds an explicit check.