ButterShare

ButterShare is a browser-based peer-to-peer file transfer tool that streams files directly between two devices over an encrypted WebRTC connection, with no cloud storage step, no account, and no application-level size cap.

What is ButterShare?

ButterShare accepts files or complete folders as input and outputs a share link, QR code, or 8-character room code that the recipient opens in any modern browser to receive a live byte stream. It runs entirely inside the browser on Windows, macOS, Linux, iOS, Android, and ChromeOS, so neither sender nor receiver installs a companion app. The project is maintained by an individual developer — the site links to the developer's LinkedIn profile rather than a company page. Data is written to the recipient's disk in chunks via the browser's Origin Private File System (OPFS) rather than being buffered fully in memory.

What makes ButterShare stand out?

• Direct device-to-device streaming — file bytes travel straight from the sender's machine to the recipient's, and nothing is written to an intermediary cloud database under a normal peer-to-peer connection.
• No application-level file-size cap — the practical ceiling is set by the device's free disk space, browser limits, and network conditions, with support for up to 10,000 files per session.
• Three invite methods — a share link, a scannable QR code, or a short 8-character room code, all without signup on either end.
• Chunked encryption — each 64KB chunk is sealed with session keys held only by the two connected devices, so the relay cannot decrypt payloads.
• TURN relay fallback — when a direct path is blocked by a firewall, WebRTC switches to an encrypted DTLS relay that forwards packets without storing file data.
• Resumable transfers — if a connection drops mid-transfer, ButterShare restarts from checkpoint data kept locally in the browser.
• Folder tree preservation — nested directory structures arrive intact, so project trees and deep directories stay organized.
• Browser coverage — Chromium-based browsers (Chrome, Edge, Brave, Opera) and Firefox stream large transfers to disk via OPFS, while Safari works under stricter browser memory constraints.

Who should use ButterShare?

• Video editors and filmmakers — hand off 50GB–200GB raw footage batches in ProRes 4444, 8K B-roll, MKV, or DaVinci Resolve projects to colorists and directors without upload queues.
• Game developers and 3D artists — ship Unreal Engine 5 assets, Blender .blend files, Unity projects, and FBX files between studios at local network speeds.
• Developers and DevOps engineers — move PostgreSQL dumps, Docker .tar images, and Linux ISOs machine to machine without leaving a copy in third-party storage.
• Music producers and audio engineers — exchange 24-bit 96kHz WAV stems and Ableton or Logic session folders at full bit depth.
• Legal and enterprise teams — transfer NDA blueprints, financial audits, and M&A documents when policies rule out third-party cloud file storage.

What can you do with ButterShare?

• Send a 100GB+ project folder: drop the directory into the browser, share the generated link, and the nested structure arrives on the recipient's disk without zipping or upload waiting.
• Move builds between machines on the same Wi-Fi: transfers between two computers on one network run at local gigabit bandwidth and consume no mobile data.
• Collect footage on set: pair a phone with a laptop across Android, iOS, Windows, or macOS tabs without cables or a companion app.
• Resume a broken large file: reconnect after a dropped session and the transfer continues from stored checkpoint data instead of restarting.

How does ButterShare work?

1. The sender selects files or a folder — no manual ZIP step and no size cap at selection time.
2. ButterShare returns a share link, QR code, or 8-character room code that the sender passes along over WhatsApp, Slack, iMessage, or email.
3. When the recipient opens the link, both browsers negotiate a WebRTC connection and files stream in 64KB encrypted chunks straight to the receiver's storage.

Pricing

ButterShare is free to use and the page describes it as "100% Free Forever," with no account tiers, subscription upsells, or paid plan listed. Its comparison table contrasts this with paid tiers at other services for a 50GB transfer.

Alternatives

• WeTransfer — its free tier caps transfers at 2GB and stores uploaded files on servers for 7 days.
• Google Drive — requires a Google account and shares out of a 15GB total storage pool.
• Dropbox — requires a Dropbox account and a 2GB free-tier transfer size.

FAQ

Do I need an account to use ButterShare?

No. ButterShare requires no account, registration, or login on either side. Transfer sessions use ephemeral 8-character room codes that expire automatically, and the sender can hand the recipient a link or QR code instead of inviting them into a workspace.

Is there really no file size limit?

ButterShare applies no application-level size cap, and the page cites free transfers above 100GB. The real maximum depends on the device's free disk space, the browser's capabilities, and network conditions. Up to 10,000 files can be sent in a single session.

Are files stored in the cloud?

During a direct peer-to-peer transfer, file data never passes through ButterShare servers or cloud storage. If a direct path fails behind a firewall, WebRTC falls back to an encrypted TURN relay that forwards DTLS-encrypted packets without storing file data.

Which browsers and devices are supported?

ButterShare runs on Windows, macOS, Linux, iOS, Android, and ChromeOS through a modern browser. Chromium browsers and Firefox stream large transfers to disk via OPFS; Safari supports transfers but is limited by browser memory constraints rather than disk streaming.

What happens if the transfer is interrupted?

If the connection drops mid-transfer, ButterShare supports resumable transfers using checkpoint data stored locally in the browser, so the session can pick up rather than start over. The recipient also needs enough free disk space to hold the incoming file.