Transparent by design
Your data stays
between your devices.
LanCopy connects browsers directly. Files and chats are not uploaded to our server or stored in a cloud account. The visible conversation exists only in this browser tab and is discarded when the page is closed.
What is transferred directly?
After the connection is established, chats and files travel through an encrypted WebRTC data channel between the participating browsers. The browser selects the available network route; devices on the same LAN normally communicate directly inside that network.
What is end-to-end encrypted?
LanCopy encrypts chat messages, file contents and file metadata—including filename, size and media type—in the browser before sending them. This application-level encryption is additional to HTTPS and WebRTC transport encryption. The keys remain in the participating browser sessions.
Which data does the signaling server process temporarily?
A small signaling service is needed so devices can find each other and establish WebRTC. It can necessarily process:
- the requesting IP address, time and device display name;
- the temporary network grouping and a random browser-session identifier, visible to other devices in the same group;
- WebRTC signaling data such as connection candidates. The browser also contacts the configured STUN service (currently Cloudflare), which can see its network address.
The LanCopy application does not intentionally retain or archive this information. Its active records are short-lived: inactive device entries are deleted during later API cleanup after about 60 seconds, delivered signaling events on the next poll and undelivered events after five minutes. SQLite journal pages, hosting backups and ordinary provider logs may follow the hosting provider's own retention rules. These operational records contain no chats, filenames or file contents.
What LanCopy does not store
- No files or file contents
- No filenames or chat histories
- No analytics, advertising profiles or tracking cookies
- No LanCopy user account
Your chosen device name and language are stored only in your own browser. As with practically every hosted website, the hosting provider may maintain ordinary access or security logs outside the LanCopy application, for example IP address, requested URL and time.
Security limits
A QR code or secure invitation link contains a high-entropy bearer secret after the # character. Anyone who obtains that link is treated as invited; it can remain in browser history, clipboard or browser sync and should be shared privately. Browsers do not send the fragment to the server, and LanCopy uses it to authenticate the end-to-end key exchange. Automatic nearby grouping is based on the public IPv4 address or IPv6 /64—not proof of a physical LAN—so VPN, proxy or provider NAT can group unrelated devices. Without the same invitation link, data remains end-to-end encrypted but identity is unverified until the safety codes are compared. A relay, if used, can see encrypted packet sizes and timing, not their contents. Compromised end devices, browser extensions or JavaScript modified before delivery remain outside this protection.