ButterShare — Send Anything, to Anyone. No File Limits

ButterShare offers a direct, peer-to-peer file transfer solution that bypasses cloud storage and eliminates file size limitations. This browser-based tool enables users to send anything, from photos and 4K videos to entire folders, directly between devices. Unlike traditional services, ButterShare does not require any signup or account creation, making the process quick and accessible for everyone.

The core functionality of ButterShare relies on WebRTC technology to establish an encrypted connection between the sender and receiver. Files are streamed in real-time and written directly to the recipient's disk using the browser's Origin Private File System (OPFS). This direct streaming method ensures high transfer speeds and maintains the privacy of your data, as files do not pass through any third-party servers or cloud storage during a direct connection.

ButterShare supports a wide range of devices and modern browsers, including Windows, macOS, Linux, iOS, Android, and ChromeOS. While Chromium-based browsers and Firefox offer the most robust experience with OPFS disk streaming for large transfers, Safari also supports transfers with browser memory constraints. The service is designed for simplicity, featuring a streamlined three-step process: choose files, share a link, and stream directly. This eliminates the need for manual zipping or waiting for upload queues.

Security is a key aspect of ButterShare. All data transferred is end-to-end encrypted, with cryptographic keys held exclusively by the two connected devices. Even if a direct connection fails and the transfer falls back to a TURN relay, the traffic remains encrypted. Furthermore, ButterShare supports resumable transfers, allowing sessions to be continued if the connection drops mid-transfer, with checkpoint data stored locally in the browser. This makes it a reliable option for sending large files without interruptions.