Simple first. Local first.

How SEYFR Sends a File

Choose your files and SEYFR prepares them locally on your device. It gives you a small QR code and text ticket to share—not a QR code stuffed with your files. The receiver scans or pastes it, chooses where to save, and receives the files from your device.

Download SEYFR Free
Mac · Windows · Linux · Android · iPhone
Cross-Platform & Account-Free

Your files. Your devices. Your choice.

SEYFR gives you fast, private file transfer across iPhone, Android, Mac, Windows, and Linux—with no accounts, no sign-ups, no subscriptions, and no cloud-storage detour.

Family & Memories

Send Original Photos to Family

Share full-resolution photos, Live Photos, and home videos without the compression, downsizing, or expiring links common in messaging apps and cloud email attachments. Every image arrives untouched.

Cross-Ecosystem

Move Large Videos from Android to Mac

Move 4K video clips, podcasts, and massive project folders between platforms that normally refuse to cooperate. No cables, no iTunes sync, and no third-party USB driver utilities required.

Offline Freedom

Transfer Files Completely Offline

Send documents and media on airplanes, subways, or off-grid remote areas. Tether to a phone's mobile hotspot or connect to a local Wi-Fi router; files stream directly between devices without internet access.

Concept illustration of file transfer between a phone and computer; not an actual SEYFR interface Concept illustration, not an app screenshot.

Prepared on your device

Your files do not take a cloud-storage detour.

SEYFR prepares a local shareable copy of the files you select. Preparation uses storage on the sending device, so it needs enough free space. Received files also need space at their destination. There is no upload to a JITPOMI cloud drive before the transfer.

Flexible Connectivity

Nearby or across the world.

Use a shared local network for nearby transfers, or an internet connection on both devices when sending farther away.

Nearby Over Local Wi-Fi or Hotspots

When devices share a local Wi-Fi router or phone mobile hotspot, SEYFR discovers nearby peers using local multicast DNS (mDNS). Files can transfer over the shared local network without internet access. Speed depends on devices and network conditions.

Across the Internet, Anywhere in the World

Need to send a file to a remote collaborator across town or family overseas? SEYFR connects devices across separate Wi-Fi networks and mobile carriers using encrypted rendezvous records published to the public Mainline DHT (BEP 44). No port forwarding, dynamic DNS, or router configuration needed.

What happens when Wi-Fi or mobile data changes? See the recorded test →

Adaptive Delivery

A connection built around your files.

Firewall Firewall DIRECT OR RELAY
Zero Cloud Detours

Direct When Possible, Encrypted Relay When Needed

SEYFR uses Iroh for encrypted connections and verifies file data while receiving.

  • Direct peer-to-peer over QUIC.
    Iroh attempts NAT traversal to establish a direct, authenticated QUIC connection when the network allows it.
  • Encrypted relay fallback.
    If strict corporate firewalls or symmetric NATs block a direct path, relays forward encrypted traffic without access to the file contents. SEYFR does not stage files on a cloud drive.
  • Continuous BLAKE3 verification.
    Files stream in content-addressed blocks verified incrementally against 32-byte BLAKE3 hashes before being exported to disk. Corrupted blocks are rejected immediately.
Safety & Consent

You decide what comes in.

You stay in total command of your storage, who can reach you, and when transfers stop. Nothing enters your device without your consent.

Receiving Approval by Default

Incoming file offers require your approval unless you explicitly enable auto-receive. You see the sender's device name, exact file name, format, and total size before deciding to Accept or Decline. SEYFR checks available destination space when possible during receiving.

Optional Auto-Receive

For your own trusted devices—such as moving photos from your personal phone to your laptop, or between close family members—you can toggle auto-receive for that specific device to skip manual acceptance prompts and receive files immediately.

Saved Devices & Presence

Save frequent devices locally as unilateral contacts. SEYFR checks saved devices using direct presence pings when reachable, with encrypted rendezvous records on the public Mainline DHT rather than unencrypted public broadcasts.

Cancel One Transfer at a Time

You can request cancellation of an individual transfer without cancelling your other transfers. Stopping a transfer may take a moment while ongoing work shuts down. For successful targeted transfers, save confirmation releases temporary ownership; original files remain intact on the sender.

Get Started Free

Ready for your next transfer?

Free file transfer across iPhone, Android, Mac, Windows, and Linux. No account or email needed.

Direct downloads below are SEYFR 2.1.4, the latest stable release. App store availability may vary by platform.

Apple iOS & Mac

Native SwiftUI apps for iPhone, iPad, and macOS.

Windows 10 / 11

Native WinUI 3 application with store & direct installs.

Android Phone & Tablet

Native Jetpack Compose app on Google Play or direct APK.

Linux x86_64

Native GTK 4 / Adwaita AppImage with GPG verification.

Seyfr CLI Terminal

Headless terminal transfers for automation, servers, and scripts.

cargo install seyfr-cli All Releases & Tags →
Technical Reference

The details behind the transfer.

For software engineers, security researchers, and technical evaluators who want to review the networking protocols, cryptographic primitives, and architecture powering SEYFR.

Technical Review: SEYFR Engineering Team | Reviewed: | Architecture described: SEYFR 2.1.x
SEYFR source code is private. Ask a technical question Iroh Protocol Docs ↗

How the SEYFR architecture works

SEYFR’s native apps call a shared Rust transfer core through UniFFI bindings, built and packaged by JFFI. The Rust CLI calls the core directly. The core uses OS-protected storage for the device identity, alongside file safeguards, saved devices, and transfer approval.

Local mDNS and encrypted rendezvous records on the public Mainline DHT help devices find each other. Iroh carries encrypted transfers directly when possible, with relay fallback when needed. File data is verified with BLAKE3 while receiving.

For targeted transfers, receiver save confirmation releases the sender’s temporary transfer ownership. Cleanup happens separately; the sender’s original files remain intact.

Explore the SEYFR 2.1 architectureApps, shared core, and networking
What SEYFR Is Today (v2.1)
Account-free file transfer across iPhone, Mac, Android, Windows, and Linux, backed by a shared Rust core:

Scroll horizontally to explore the full diagram.

SEYFR 2.1 system architectureNative apps call the shared Rust core through UniFFI. The CLI calls it directly. OS-protected identity, consent, saved devices, and transfer management use Iroh transport with local discovery and encrypted DHT rendezvous. CLIENTS & NATIVE APPS macOS (SwiftUI) iOS (SwiftUI) Android (Compose) Windows (WinUI 3) Linux (GTK 4 / Adwaita) Seyfr CLI (Rust / Terminal) UniFFI Language Bindings Type-safe bindings, cross-platform lifecycle & callbacks • Packaged by JFFI Direct crate dependency (No FFI) OS-Protected Identity Storage Apple Keychain • Android Keystore (AES-GCM) • Win Credential Mgr • Linux Secret Service (via keyring) SHARED RUST CORE (seyfr-core) Identity & File Safeguards • Protected Identity: Installation keypair (iroh::SecretKey) • Path Jail & Storage Guard: Traversal protection, disk checks Control & Signaling Plane (ALPN: /seyfr/transfer-control/1) • Targeted Offers: Name, size, mime preview • Up to 5 slots • Save Finalization: Saved/SavedAck: releases temporary transfer ownership Transfer & Job Management • Per-Job Registry: Job-id tokens & cancel_transfer • Metadata + HashSeq format for single files & folder collections • Periodic Maintenance: Blob GC & import expiry every 60s Saved Devices & Presence • Saved Devices Store: Unilateral contacts & pairings • Live Presence Probes: PresencePing / PresencePong liveness • Connection Orchestration: Races Iroh hints vs. encrypted DHT Stats Engine: Bandwidth tracking, speed calculation & local transfer history Tracks throughput per-transfer without phone-home telemetry PEER DISCOVERY (FINDING DEVICES) Local mDNS (LAN peer discovery) Encrypted rendezvous records on public Mainline DHT (BEP 44) IROH CONNECTION TRANSPORT (CARRIES CONNECTIONS) Direct P2P QUIC Connections • NAT Traversal Attempts • End-to-End Encrypted Relay Fallback Control Protocol /seyfr/transfer-control/1 Device Info Protocol /seyfr/device-info/1 iroh-blobs BLAKE3 verified streaming iroh-gossip Progress & coordination
Native apps, shared core

One core. Familiar interfaces.

The native apps use SwiftUI on Apple platforms, Jetpack Compose on Android, WinUI 3 on Windows, and GTK 4 / Adwaita on Linux. UniFFI connects these interfaces to the shared Rust transfer core; JFFI builds and packages the native integrations. The Rust CLI calls the core directly.

Security First

The Rust Core Vault

Our Rust core applies the same destination and file-handling checks across supported platforms:

  • Destination Path Validation: Uses path_jail to keep received paths inside the destination the user selected and reject traversal attempts.
  • Safer File Handling: Rust memory safety reduces important classes of memory errors; it does not make software immune to every defect.
  • Folder Collection: Walks non-empty folders, skips nested hidden directories and node_modules, and preserves relative file paths.
Architectural History: When SEYFR First Launched (v1.0) Click to view ↓
When SEYFR first launched, it was a one-way delivery pipe:
You picked a file → got a ticket code → sent it over the internet to another device.
That was it: no contacts, no previewing files before receiving, and no way to cancel just one transfer. Here is how that initial architecture looked:
JFFI Developer Framework (Power of Rust, Charm of Native) macOS (SwiftUI) Android (Compose) Windows (WinUI 3) iOS (SwiftUI) Linux (GTK 4) JFFI & UniFFI Bridge Connects each native app to the shared Rust core Shared Rust Core (seyfr-core) Local storage, content addressing, transfer and file checks Connection Routing Relay helps connect, then steps back when direct works iroh Content-Addressed Blobs 32-byte BLAKE3 address; verified while streaming iroh-blobs
Read the protocol & blob storage details
In technical terms, SEYFR imports selected bytes into its local Iroh blob store and creates a HashSeq linking a separate SEYFR metadata blob to the file blobs. The ticket contains the sender's Iroh endpoint address, the 32-byte BLAKE3 root hash identifying that HashSeq, and the HashSeq format—not file bytes or file metadata. The receiver fetches the HashSeq, metadata and files separately. Iroh verifies downloaded blob data incrementally against its BLAKE3 hash tree before SEYFR exports each file to the chosen destination. Read Iroh's Blobs documentation.

Phone to computer

Send the original file to the computer you already use.

Move photos, videos, folders and documents between supported devices—without creating an account or uploading them to cloud storage first.

Download SEYFR free Ask if SEYFR supports your setup →

Transfer speed depends on your devices and network.

Concept illustration of SEYFR transferring files between a generic phone and laptop; interface panels and speed are illustrative, not actual product claims