The tfile.io service enables direct browser-to-browser file transfers using WebRTC, bypassing servers for data transmission. A signaling server built on TypeScript and WebSocket handles initial connections, while WebRTC data channels manage the actual file exchange.
To ensure security and stability, the system uses HMAC-SHA256 tokens for session IDs and implements a custom flow control mechanism. This mechanism, functioning like a mini-TCP layer, prevents the SCTP stack from overwhelming the network with large data bursts.
The platform addresses connectivity issues with TURN servers, using a REST API for short-lived credentials. It also optimizes performance by detecting local network peers to avoid unnecessary relay traffic and uses CompressionStream for efficient data transfer.
Large file handling is managed via the Origin Private File System (OPFS), which allows writing data directly to disk instead of memory. Web Locks are used to manage file cleanup, ensuring that temporary data is removed only when the associated browser tab is closed.
