SyntroSend

SyntroSend for Mac is a powerful peer-to-peer (P2P) and zero-knowledge hybrid file transfer application that enables direct, secure, and ultra-fast file sharing

Built on the advanced Iroh protocol, SyntroSend allows you to transfer files 100% offline over the same Wi-Fi network at gigabit speeds, or globally through end-to-end encrypted peer-to-peer tunnels. When recipients are offline, optional SyntroCloud provides client-side encrypted asynchronous delivery and a permanent cloud vault—ensuring your files never touch a server in plaintext.

Features:

100% Offline Local Transfer: Share files and folders over local Wi-Fi / LAN with maximum network speeds and zero internet bandwidth usage.

Global P2P Connections: Send files across the globe through direct encrypted QUIC and NAT-traversing relay tunnels.

No File Size Limits: Transfer 100 MB, 10 GB, or 100 GB. Direct transfers have zero arbitrary file size restrictions.

SyntroCloud & Offline Delivery: Recipient offline? Deliver files asynchronously via SyntroCloud using Client-Side AES-256-GCM Zero-Knowledge encryption.

Syntro Inbox & 1-Click Contacts: Pair your devices or trusted peers once using a simple 4-digit code for instant 1-click delivery—no transfer codes needed ever again.

ClipShare (Universal Clipboard): Instantly beam copied text, code snippets, and URLs across all your connected devices in real-time.

Public & Private Group Channels: Create secure rooms for up to 10 members with 6-digit invite codes, custom group avatars, and granular admin controls.

Floating DropZone Widget: Always-on-top transparent desktop dropzone for instant drag-and-drop file sharing anywhere on your screen.

Windows Context Menu Integration: Right-click any file or folder directly in Windows Explorer to send via SyntroSend instantly.

Nearby Device Discovery: Automatically discover and pair with nearby devices on the same local network.

Multi-Device Account Sync: Optional account login automatically backs up and syncs your paired contacts, avatars, and preferences across all devices.

47 World Languages: 100% deep native localization across 47 international languages with seamless instant switching.

Custom Sounds & Avatars: Choose personalized profile avatars and notification sounds.

No Signup Required: Start sending immediately in Guest Mode without creating an account.

Security & Reliability:

Client-Side End-to-End Encryption: Direct streams are protected via the Noise protocol & TLS 1.3; cloud transfers use Client-Side AES-256-GCM.

Double-Envelope Master Key Hierarchy: Cloud Vault keys are sealed locally under your password and a mandatory 32-character Emergency Recovery Key. Zero plaintext keys exist on any server.

BLAKE3 & AEAD Integrity Verification: Real-time cryptographic hashing verifies every chunk before saving to disk, preventing bit-rot and data tampering.

Smart Auto-Resume: Interrupted transfers automatically resume from the exact byte where they stopped without restarting.

In-Memory Streaming: Decrypted files stream directly to their destination with zero unencrypted temporary scratch files on disk.

How it Works:

Select Files or Folders: Drag & drop any file or folder into SyntroSend or the Floating DropZone.

Choose Transfer Mode:

Direct Ticket: Generate a secure code or QR code to share with your peer.

Syntro Inbox: Select a paired contact for instant 1-click delivery.

SyntroCloud: Drop files to offline contacts for zero-knowledge cloud delivery.

Instant Transfer: Start instant direct streaming or background encrypted upload with live progress tracking.

Why SyntroSend?

Unlike traditional cloud storage services that upload your plaintext data to centralized data centers and hold your master keys, SyntroSend prioritizes direct peer-to-peer streaming and 100% mathematical zero-knowledge privacy.

For real-time transfers, files stream directly between devices over local Wi-Fi or encrypted global tunnels without touching any intermediate server. When recipients are offline, optional SyntroCloud provides seamless asynchronous delivery and a permanent cloud vault protected by Client-Side AES-256-GCM Encryption and a Double-Envelope Master Key Hierarchy. Your cryptographic keys remain strictly on your local devices sealed under your password and a 32-character recovery key—guaranteeing that neither SyntroSend nor any cloud provider can ever access, inspect, or decrypt your data.

Whether you are transferring massive 4K video projects, multi-gigabyte folder structures, or everyday documents, SyntroSend delivers a lightning-fast, private, and unrestricted file sharing experience across Windows, macOS, Linux, and Android.