LocSend Directly transfer files and messages between phones and computers on the same Wi-Fi/wired network/IPv6 public network: No registration required, no public network access needed, no cloud traffic involved. End-to-end encryption ensures both security and efficiency.
No registration required, no public network access needed, no cloud traffic involved. End-to-end encryption with support for text and large file transfers.
No detours—bandwidth depends on your Wi-Fi 6/7 or wired network, easily reaching gigabit speeds.
Using DTLS + SRTP, encrypted data is transmitted only between devices after the handshake and does not pass through the server.
No installation required—simply open the webpage to use; P2P peer-to-peer connection.
Windows、macOS、Linux、Android、iOS Available on all browsers.
Supports files, images, text messages, and clipboard;
Optional private signaling deployment/internal STUN, domain and IP range locking to meet compliance requirements.
Signaling is the information browsers use to find and connect to each other when establishing a peer-to-peer (P2P) WebRTC connection. In offline mode, this information is exchanged manually; in online mode, it is exchanged automatically through a server, while all actual data is still transmitted directly between peers.
You are using the true offline version — pay attention to the word “true”.
The true offline version has no servers involved at all. Signaling must be manually exchanged by both sides, and once the connection is established, there is no automatic reconnection mechanism.
So-called P2P direct connection means that browsers generate connection addresses (ICE candidates) based on the WebRTC protocol.
Even on the same computer with two browsers, they are still treated as two independent nodes establishing a direct P2P channel. Stability therefore depends entirely on the local network, operating system, and browser state.
As a result, if the true offline version disconnects or becomes unstable after about one minute, this is usually not a program bug, but normal behavior of WebRTC without any server-side fallback.
There are only two solutions:
1️⃣ Refresh the page and manually exchange the signaling again
2️⃣ Use the online version — the online version supports automatic reconnection after disconnection and is significantly more stable
The true offline version prioritizes zero servers, zero dependencies, and absolute privacy, not connection stability. This trade-off needs to be understood.
LocSend The offline version is designed for users seeking ultimate security and privacy protection. Unlike other messaging and file transfer software that submit data to servers—posing privacy risks and imposing file size limits—this offline version sacrifices convenience by having users exchange signaling themselves. It achieves truly serverless, locally-run HTML files, ensuring security and reliability!
LocSend IPv4 environments without public IP addresses only support local area networks, while IPv6 supports public network connections. P2P enables direct peer-to-peer connections without any relayed traffic, ensuring privacy, security, and reliability.
There is no file size limit, but some browsers do not support selecting a save location before transfer and will automatically default to memory transfer, which consumes significant device memory. For files larger than 2GB, we recommend using native browsers like EDGE or CHROME that fully support selecting a save location. Transfer speed is then limited only by the network connection, CPU performance, and disk write speed of both devices.
Some mobile systems restrict network access and JavaScript timers in the background. It is recommended to keep the screen on in the foreground during transmission or use a desktop browser.
In pure browser mode, LAN auto-discovery relies entirely on the server identifying devices via their public IP addresses. This allows anyone to join large LAN environments—such as campus networks, NAT-shared networks, or corporate networks—posing security risks. Locsend supports direct connections in environments without a public IPv4 address or with a public IPv6 address. Therefore, by using temporary room IDs and passwords, you can confidently establish your own private transmission environment, ensuring secure transfers!
The validity period for free temporary room numbers in the online version is 24 hours. Room numbers can be canceled in advance. Room numbers will be automatically destroyed after exceeding 24 hours.
If both parties are on the same local network and use private IPv4 addresses (192.168.x / 10.x / 172.16.x), WebRTC traffic is transmitted directly over the local TCP / UDP network. It does NOT go through the ISP’s public network, does NOT pass through external NAT or WAN routing, and therefore cannot be affected by ISP-level QoS. The speed depends only on the network card, switch, and Wi-Fi quality — equivalent to copying files within a LAN or transferring data to a NAS.
If both parties have public IPv6 connectivity, WebRTC establishes a direct connection using IPv6 addresses, without TURN relays or server forwarding. This traffic does traverse the ISP network (because IPv6 is public), but it is still ordinary point-to-point traffic. There is no “P2P feature server” and no “central node that can be targeted”. From the ISP’s perspective, it is almost indistinguishable from scp / sftp / https downloads.
Conclusion: There is no “special QoS targeting”. At most, ISPs may apply uniform bandwidth policies to all users, but they will not identify or selectively throttle LocSend / WebRTC / P2P tools.
QQ Group: 709193338
Telegram Group: https://t.me/locsend
The community source code is being built on LOWPHP — stay tuned!
Copyright & Disclaimer
This project (LocSend) is independently designed and developed by the author, with its own implementation and technical approach.
This project is not an official version, derivative project, or collaborative outcome of any third-party similar project. It has no affiliation, partnership, authorization, or association with other similar projects or their respective teams.
LocSend is a browser-based peer-to-peer (P2P) file transfer tool built on WebRTC technology. All data is transmitted directly between user devices without being stored or relayed by any server.
This statement is provided solely to clarify project independence and technical positioning, and does not express any evaluation, comparison, or commercial stance toward third-party projects.
