ButterShare

ButterShare is a browser-based peer-to-peer file transfer tool that streams files directly between two devices over an encrypted WebRTC connection.

To send, choose files or an entire folder in your browser, then share an instant link, QR code, or a 6-character room code with your recipient. The recipient opens it in any modern browser, and the two devices establish a direct connection so the files stream in real time without uploading to cloud storage. During transfer, file bytes are written to disk in chunks using the browser’s Origin Private File System (OPFS), enabling large transfers without requiring you to manually ZIP content first.

ButterShare is designed for cross-platform transfers across Windows, macOS, Linux, iOS, Android, and ChromeOS. Chromium-based browsers and Firefox support large transfers via OPFS disk streaming, while Safari uses browser memory constraints. There’s no application-level file-size cap—practical maximums depend on available disk space, browser capabilities, and network conditions. Transfers can also handle connection interruptions with resumable transfers using checkpoint data stored locally in the browser.

If a direct peer-to-peer path can’t be established (for example, behind certain firewalls), ButterShare falls back to an encrypted TURN relay so the transfer can continue; the relay forwards encrypted traffic and does not store file data. ButterShare is free to use, offered as “100% Free Forever” for sending transfers.

Do I need to create an account or install an app to use ButterShare?

No. ButterShare runs in the browser and doesn’t require account registration, login, or an app install.

Is there a file size limit for transfers?

ButterShare doesn’t impose an application-level file-size cap. Practical limits depend on factors like device disk space, browser capabilities, and network conditions.

Does ButterShare upload my files to cloud storage?

During a direct peer-to-peer transfer, file data doesn’t pass through cloud storage or any ButterShare server. If direct connection fails, an encrypted TURN relay is used to forward encrypted traffic without storing file data.

Can I transfer folders and keep the folder structure?

Yes. You can select a folder and ButterShare preserves the directory hierarchy so nested folders arrive organized as they were sent.

What happens if the direct connection can’t be established or drops mid-transfer?

If a direct peer-to-peer path can’t be made, ButterShare automatically uses an encrypted TURN relay. If the connection drops mid-transfer, resumable transfers are supported using local browser checkpoint data.

Which browsers and devices does ButterShare support?

ButterShare works on any device with a modern browser, including Windows, macOS, Linux, iOS, Android, and ChromeOS. Chromium-based browsers and Firefox support large transfers via OPFS disk streaming; Safari supports transfers with browser memory constraints.