Why peer-to-peer (P2P)? How does ButterShare work?

Peer-to-peer communication means files stream directly between two devices rather than being uploaded to an intermediate cloud server. ButterShare achieves this using WebRTC (Web Real-Time Communication), an encrypted web standard built into modern browsers. Because you completely skip the slow upload-then-download cloud cycle, transfers are faster, completely private, and have zero server file size limits.

Is there really no file size limit? How does this compare to WeTransfer?

Unlike WeTransfer which caps free transfers at 2GB and charges $12/month for larger files, ButterShare has zero file size limits. Files stream directly between your device and the recipient's device with 100% privacy. Because zero bytes are stored on a cloud server, you can send 10GB, 50GB, 100GB, or even larger files and folders without paying a dime.

How long are files stored in the Cloud?

We don't store anything! Your files are never uploaded to any cloud server, database, or cache. Once the transfer completes or either person closes their browser tab, the room is destroyed and zero bytes remain on any server.

How long does a transfer link stay active?

A transfer link remains active as long as the sender keeps their browser tab open (up to 2 hours of room activity). If the sender closes their tab or shuts down their computer, sharing stops immediately because the files are being delivered directly from their device.

Does the recipient need to install an app or register an account?

No. The recipient simply opens your shared transfer link (or scans the QR code). The transfer initiates immediately inside their standard web browser on any phone, tablet, or computer. No accounts, no passwords, and zero app installs required.

Why is the transfer speed slower than my maximum internet download speed?

In a direct peer-to-peer transfer, your speed is bounded by the slower of the two connections: the upload speed of the sender or the download speed of the receiver. Most home internet connections offer fast download speeds (e.g. 200 Mbps) but much slower upload speeds (e.g. 15–25 Mbps). If the sender's upload speed is 20 Mbps, the receiver can only receive data at 20 Mbps. Wi-Fi interference, distance between routers, and corporate firewalls can also affect transfer speeds.

How can I increase the transfer speed?

Here are the most effective ways to maximize speed: (1) Connect both devices to the same local Wi-Fi network: ButterShare automatically detects Local Wi-Fi (LAN) and streams data directly through your router at speeds up to 500+ Mbps without consuming internet broadband. (2) Connect at least one computer via an Ethernet cable. (3) Keep both browser tabs in the foreground. (4) If using a mobile phone, keep the screen unlocked and close heavy background apps.

Can I transfer files between devices on the same Wi-Fi without using mobile data?

Yes! When both devices are connected to the same Wi-Fi router or local network, ButterShare automatically routes the connection directly over your LAN. Your transfer stays inside your local network, runs at local Wi-Fi speeds (often 300–800 Mbps), and consumes zero mobile data or ISP internet quota.

The transfer starts downloading but then stops halfway. Why?

This almost always happens due to one of two platform limitations: (1) Safari Memory Limits: Safari on iOS and Mac loads files into browser memory rather than streaming directly to disk. For transfers over 2GB–4GB, Safari can hit its memory ceiling and terminate. We advise using Google Chrome, Mozilla Firefox, or Microsoft Edge on a computer for massive files. (2) Mobile Screen Sleep: iOS and Android kill active WebRTC connections when the screen turns off or when you switch apps to save battery. Always keep your screen awake and the ButterShare tab in the foreground until the transfer hits 100%.

The progress bar is stuck at 0% or says connection error. What happened?

A progress bar stuck at 0% typically means a direct peer-to-peer path could not be negotiated. This occurs on strict corporate firewalls, university campus networks, hospital networks, or when a commercial VPN is active. Try disconnecting your VPN, switching from Wi-Fi to a mobile hotspot, or restarting the transfer to discover a fresh network path.

It says 100% completed, but where is my file?

Your file is saved in your browser's default downloads location. On Windows and Mac, press Ctrl+J (or Cmd+Option+L on Mac) to view recent browser downloads. On iPhone and iPad, open the built-in 'Files' app and navigate to 'Downloads' or 'On My iPhone'.

What happens if I accidentally close the tab during a transfer?

Because ButterShare streams data live between paired devices, closing either tab will terminate the transfer. However, ButterShare now includes active tab protection: whenever files are being shared or transferred, your browser will display a confirmation dialog ('Leave site? Changes you made may not be saved') to prevent accidental tab closures.

What web browsers and operating systems are supported?

ButterShare works on any device running a modern browser: Google Chrome (Windows, Mac, Android, Linux, ChromeOS) — Recommended with unlimited file size; Mozilla Firefox (Windows, Mac, Linux) — Recommended with unlimited file size; Microsoft Edge (Windows, Mac) — Recommended with unlimited file size; Brave & Opera — Full support; Apple Safari (Mac, iOS) — Full support up to ~4GB (limited by Apple's browser memory sandbox).

Can I send entire folders or multiple files at once?

Yes! You can drag and drop multiple files or entire folders. On the receiver side, you can download files individually or click 'Download All as ZIP' to download every file packaged into a single archive directly on your device.

How secure is the transfer? Can anyone intercept my files?

All WebRTC data channels are encrypted with DTLS (Datagram Transport Layer Security) using AES-128 or AES-256 ciphers, negotiated directly between the two browser endpoints. When a direct peer-to-peer path is available, file data travels straight between devices without touching any server. When firewalls prevent a direct path, WebRTC falls back to a TURN relay that forwards DTLS-encrypted packets between the two endpoints. The relay infrastructure cannot decrypt the payload. In both cases, file bytes are never stored on any server.

Why is ButterShare completely free? What's the catch?

Because ButterShare does not store your files on expensive cloud storage infrastructure (like AWS S3 or Google Cloud), our operational costs are negligible. We don't have multi-thousand-dollar cloud storage bills to pay each month, which allows us to offer ButterShare 100% free with no file size limits and zero subscription fees.

ButterShare

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Send Large Files Online Free,No Size Limits

Send 10GB, 50GB, or larger files directly between devices through a secure link. Fast peer-to-peer sharing with zero cloud storage, no signup, and end-to-end encryption.

Drop any files or folders here

Send anything — photos, 4K videos, documents, or entire folders without size limits.

Learn How It Works

About ButterShare

Direct device-to-device file transfer

ButterShare is a browser-based peer-to-peer file transfer tool. It streams files directly between two devices over an encrypted WebRTC connection without uploading them to cloud storage.

How does ButterShare transfer files?

The sender selects files or folders, and ButterShare generates a share link, QR code, or 6-character room code. The receiver opens the link in any modern browser. Both devices establish a direct WebRTC connection and files stream in real time, written to disk in chunks using the browser's Origin Private File System (OPFS).

Explore direct P2P file sharing

Does ButterShare upload files to cloud storage?

During a direct peer-to-peer transfer, file data does not pass through cloud storage or any ButterShare server. When a direct connection cannot be established (for example, behind certain firewalls), WebRTC uses an encrypted TURN relay to forward packets between devices. The relay carries DTLS-encrypted traffic and does not store file data.

Read about security & privacy architecture

Which devices and browsers are supported?

ButterShare works on any device with a modern browser: Windows, macOS, Linux, iOS, Android, and ChromeOS. Chromium-based browsers (Chrome, Edge, Brave, Opera) and Firefox support large transfers through OPFS disk streaming. Safari supports transfers with browser memory constraints.

Explore cross-platform guides & resources

Is there a file-size limit?

ButterShare does not impose an application-level file-size cap. The practical maximum depends on the device's available disk space, browser capabilities, and network conditions. Transfers up to 10,000 files per session are supported.

Learn about large file transfers

Do I need an account?

No. ButterShare does not require an account, registration, or login. Transfer sessions use ephemeral 6-character room codes that expire automatically.

View speed benchmarks & performance data

What happens when a direct connection fails?

If a direct peer-to-peer path cannot be established, WebRTC automatically falls back to a TURN relay. The transfer continues through encrypted relay transport. If the connection drops mid-transfer, ButterShare supports resumable transfers using checkpoint data stored locally in the browser.

See technical architecture & connection handling

Streamlined 3-Step Flow

Sending takes seconds, not sign-ups

No cloud storage, no waiting for upload queues, no accounts. Three simple steps and your files beam directly device to device.

01Choose Files

Select your files or folders

Drop any file or an entire directory. There are zero file size caps and no manual ZIP step before selection.

02Share Link

Upload file & share link

Get an instant share link or QR code. Send large files online by sharing the link over WhatsApp, Slack, iMessage, or email with no sign-up required.

03Stream Direct

Stream direct device to device

As soon as they connect, files stream directly between devices through an encrypted browser connection. File bytes are not saved to cloud storage.

Direct Device-to-Device

Why direct streaming is fundamentally better

Eliminate cloud queues, storage quotas, and third-party servers. Experience fast transfer speeds by connecting two machines directly with zero compromises.

NO CLOUD LIMITS

Direct P2P Stream

Direct device-to-device streaming

Files stream straight from your machine to the recipient. Nothing touches an intermediary cloud database.

Zero Storage Intermediary

Local Wi-Fi Gigabit Speed

ZERO-KNOWLEDGE

End-to-End Cipher

Direct peer-to-peer encryption

Every 64KB chunk is sealed with cryptographic keys held exclusively by the two connected devices.

Zero Server Decryption

Ephemeral Session Keys

UNLIMITED SIZE

Direct Disk Streaming

No file size limits

Send gigabytes or terabytes without compression, subscription upsells, or memory limits.

Native Disk Streaming

Large-File Streaming Pipeline

ButterShare — Your Best Choice for Unlimited, Private File Transfer

← Swipe sideways to compare all →

Features	ButterShare Direct	WeTransfer	Google Drive	Dropbox
Maximum File Size	No Limits (100GB+ Free)	2 GB (Free tier cap)	15 GB (Shared total)	2 GB (Free tier)
Experience	Instant direct transfer for any device	Upload link / wait for email	Upload to drive & share link	Upload to cloud & share
Cloud Server Storage	100% Private (0 Bytes Stored)	Stored 7 days on server	Stored indefinitely	Stored indefinitely
Transfer Encryption	Encrypted direct browser transfer	Server-side decryptable	Server-side decryptable	Server-side decryptable
Account or App Needed	None (Instant 1-Click Link)	Email verification required	Google Account required	Dropbox Account required
Cost for 50GB Transfer	100% Free Forever	$12 / month (Pro)	$2.99 / month (Google One)	$11.99 / month (Plus)

Built for Heavy Payloads

Engineered for unlimited files

From 100GB video timelines to private legal audits, ButterShare beams what legacy cloud uploaders choke on.

Multi-Gigabyte Video

Video Editors & Filmmakers

Stream massive 50GB–200GB raw footage batches directly to colorists and directors with zero upload queues or cloud penalty fees.

ProRes 4444, 8K B-Roll, MKV, DaVinci Resolve

3D & Game Builds

Game Devs & 3D Artists

Send game builds, textured environment files, and animation rigs instantly. Connections max out local network bandwidth at gigabit speeds.

Unreal Engine 5 assets, Blender .blend, Unity, FBX

DevOps & SysAdmin

Developers & DevOps

Share complete database snapshots and container images between machines with bit-level integrity and zero cloud intermediate footprint.

PostgreSQL dumps, Docker .tar, Linux ISOs

Lossless Audio Stems

Music Producers & Audio

Collaborate on album masters and stem packages with fellow musicians and engineers with pure bit-for-bit fidelity and zero file size ceiling.

24-bit 96kHz WAV, Ableton, Logic sessions

Fully Secure Privacy

Legal & Enterprise Confidential

When privacy matters, ButterShare avoids third-party cloud file storage and transfers through an encrypted browser connection.

NDA blueprints, financial audits, M&A vaults

Disk Streaming Engine

Native Direct Disk Streaming

Large transfers stream in chunks straight to storage via the Origin Private File System (OPFS). Transfer files larger than your computer's RAM with ease.

Multi-gigabyte folders, raw archives

Universal Web Compatibility

Cross-Platform Wireless Transfer

Transfer files wirelessly between Android, Windows, Mac, and iOS directly in any browser tab without cables, companion apps, or setup.

Works across all major browsers & platforms

Folder Structure Intact

Folder Tree Preservation

Send nested folder structures intact. ButterShare preserves your directory hierarchy so files arrive organized exactly as they left.

Deep directories, project trees

Frequently Asked Questions

Got questions? We've got answers

Everything you need to know about device-to-device transfers, security, file sizes, and device compatibility.

Send Any File, Any Size, Any Device

No cloud storage. Beam your file now.

Ditch the 2GB WeTransfer limits and monthly cloud fees. Send files directly between iPhone, Android, Mac, and Windows with zero accounts and zero server storage.

No 2GB File Limits

100% Private (0 Bytes Stored)

Every Device & Browser