File sharing · macOS · Windows · Android
Bifrost sends files over the internet straight from one device to another, end-to-end encrypted. Nothing is uploaded to a cloud, and an interrupted transfer picks up where it stopped.
Free and open source · No account · No size limit · 0 bytes stored on servers
This is the live app. Try Pause on the transfer, or click around.
01Privacy
Anyone can write "private" on a landing page. Bifrost gives you a receipt for every file instead, kept on both devices, that says exactly how it travelled. Here is one, line by line.
02Safety words
When a new device asks for access, both screens show five words made from the two devices' keys. Read them to each other. If they match, the connection is between you two and no one else. If anyone tried to sit in the middle, the words would be different.
03How it works
Each file travels once, from one disk to the other, and leaves a matching receipt on both devices.
Pick one folder on the device with the files. Nothing outside it can be listed, read or written.
Choose what it may do (download, upload or both) and send a 16-character code like K7QM-9XRT-4HWD-P2NA, a link or a QR code.
You see the device's name, its access and the five safety words before it can browse anything.
Each megabyte is hash-verified on arrival, and the whole file once more before it gets its name.
Progress is saved after every verified megabyte. A dropped connection, a pause, a closed laptop or a power cut loses at most the block in flight. Unfinished transfers start again when the app opens and retry as soon as the network is back.
An invitation says what its device can do: download, upload, or both. Change any device's access later from the Send page; the others keep theirs. Invitations expire, can be limited to a number of devices, and can be revoked.
The receiver sees the shared folder with names, sizes and dates, filters it, and downloads single files or whole folders to a place of its choosing. Big folders load as you scroll, so a directory with thousands of files stays quick.
A month calendar shows what came in and went out each day. See who you trade the most data with, what kind of files they are, and how much ever went through a relay. All of it is worked out on your device from your own receipts.
Send between a Mac, a Windows PC and an Android phone in any combination. On Mac and Windows, Bifrost starts when you sign in and keeps running in the menu bar or tray when you close the window. On Android, transfers keep running with the screen off and show their progress in a notification.
05Security
Two devices on the internet need a little help to find each other. Here is everything that help can see, and everything it can't.
06Compare
| Capability | Bifrost | Cloud share links | Chat and messaging apps |
|---|---|---|---|
| File size limit | None | Usually a few GB | Usually 2 GB or less |
| Travels over the internet | Once, device to device | Twice: upload, then download | Twice, through their servers |
| Copy kept on a server | Never | Until the link expires | Often |
| Resumes after a drop | From the last verified megabyte | Sometimes | Rarely |
| Verifies every byte | Yes, block by block | Varies | Varies |
| Both devices online | Required | Not required | Not required |
Bifrost trades the convenience of an always-on server for privacy and no size limits: the sender has to stay online while the receiver downloads.
07Download
Latest release. Free, no account needed. New versions install over the old one and keep your devices and history.
Bifrost is new and not yet code-signed by a certificate authority, so your system may ask you to confirm.
Every file in a release has a matching .sha256 checksum, so you can confirm it is genuine.
08Open source
Bifrost is MIT licensed. The transfer engine is a Rust library on iroh, with end-to-end tests for pauses, crashes, corruption, source changes, uploads, permissions and auto-sync. The apps use Tauri with a React interface. Issues, ideas and pull requests are welcome.
# Build and run from source
git clone https://github.com/MisbahKhan0009/Relayless
cd Relayless && npm ci
npm run tauri dev
# The interface alone, with demo data
npm run dev:ui
# Engine tests: real transfers, pauses,
# crashes, corruption, uploads
cargo test -p relayless-core --release09FAQ
Yes, while files move. If either one goes offline, the transfer waits and continues from where it stopped when both are back. It also starts again by itself when the app opens.
Some networks, mobile data in particular, block direct paths. Bifrost tries direct first and, if none opens within about 5 seconds, continues through a public relay. The data stays end-to-end encrypted, so the relay can't read or keep it, and Bifrost moves to a direct path as soon as one opens. The receipt shows how much went through the relay. If you'd rather wait for a direct path, choose Direct only in Settings.
The free public relays are rate-limited, often to around 1 Mbit/s. Turning on UPnP or IPv6 on your router usually gives a direct path. You can also run your own relay and set it under Settings, Connection, Relay server. The relay guide walks through both.
No. Files are streamed from disk in small blocks, so a 500 GB file uses the same memory as a 5 MB one. You need enough free space on the receiving side.
As fast as the slower of the two connections allows, which is usually the sender's upload speed. Twelve parallel streams per file keep long-distance links full, and on lossy direct paths the receiver can add connections to the same sender while each one raises the speed.
No. They can only reach the folder you shared, and only after you approve their device. A device allowed only to upload sees just what it added, like a drop box. You can change a device's access, stop sharing or remove a device at any time.
No. Uploads go to a temporary file, are verified, then saved under a free name, so nothing existing is replaced. A device can delete only files it uploaded itself and that you haven't changed since.
Only in the app's database on your device. Nothing is synced or uploaded. You choose how long it is kept, can keep it without file names, and can clear it at any time in Settings.
They let two people confirm, out loud or over a call, that their devices are talking to each other directly. They are derived from both devices' keys, so a device in the middle would produce different words.
Releases include an Apple silicon build for macOS; an Intel Mac can build the app from source. Linux builds are on the roadmap. There is no iPhone or iPad app.
No. Bifrost is free and open source. There is no account and no paid tier.