How I Built a Zero-Install, Multi-Gigabyte P2P File Transfer Engine in the Browser with WebRTC & File System Access API

Ever tried sending a 15GB 4K video file or a raw dataset to a teammate sitting at the next desk?

The options are surprisingly clunky:

Hunt for a physical USB flash drive.

Upload it to Google Drive, Dropbox, or Slack (wasting your internet bandwidth, hitting upload limits, and waiting for compression) only for your coworker to spend another 20 minutes downloading it back over the same local network.

I wanted to fix this with a zero-friction experience: no desktop client installation, no cloud storage limits, and full local network transfer speed directly inside the browser.