Six words to connect
Type six simple words on the other device. The handshake travels encrypted through public relays that cannot read it.
NewSend text and links too
Send files straight to your own devices.
Open filefinch on two devices, type six words, then drop your files. They fly from one device to the other, any size, end to end encrypted. No account, no upload.
- No account
- No upload
- End to end encrypted
- No size limit
Animation: a computer shows six words, a phone types them, both confirm with six more words, then three files fly from the phone to the computer and arrive checked.
Runs in the browser on
- Windows
- macOS
- Linux
- Android
- iPhone
- ChromeOS
Chrome / Edge / Firefox / Safari / Brave / Opera
How it works
Five steps. About a minute.
No account, no upload. Press a step to see it, or let it play.
Network blocks the relays? Under Options, Connect with no relays (advanced) scans a QR code each way instead.
Any size
Any size. Never held in memory.
Files are read in small chunks and written to disk as they arrive, so a 50 GB video flies the same way as a photo.
- Small 64 KiB pieces, read only a few ahead of the network.
- Written straight to disk, into a folder you pick or as a streamed download.
- SHA-256 while streaming. The receiver checks every file before marking it done.
64KiB per chunk
256bit SHA hash per file
Nosize limit set by filefinch
Resilient
Pause, resume, survive a drop.
Wi-Fi blinks, a phone sleeps, a laptop lid closes. Reconnect and the transfer continues from the last confirmed chunk.
- Resume from the last chunk instead of starting over.
- Pause and cancel from either side.
- Plain words when it fails. filefinch explains strict networks and offers the TURN setting.
Connection lostResumed from 64%
Folders
Whole folders. Two way sync.
Drop a folder and its tree flies as a flock. Or keep a folder in step between two computers, sending only what changed.
- The tree arrives intact, with sanitized paths that never escape the folder you pick.
- Two way, push or pull. Review the plan of changes before anything is written.
- Conflicts are kept, never silently overwritten.
Private by design
Your files take the direct line.
filefinch is a web page that connects two browsers to each other. After that, it steps out of the way.
- No server of ours ever sees your files or messages.
- DTLS on every connection, with keys created inside the two browsers.
- Confirm with six words. No file moves until the words typed on one screen match the other.
- Add a passphrase for a second AES-GCM layer. It never travels.
The honest part. The 6 word handshake travels through public MQTT relays, which see that two devices exchange a few small encrypted messages, never what they say. Your files never touch them. When both networks block every direct route, a TURN relay you configure can forward the encrypted traffic. To find a route, each browser asks a public STUN server for its public address, which sees your IP address like any website. With the advanced no relay option, nothing relays the handshake at all.
Library and previews
See it before you keep it.
Preview photos, video, audio, PDF and text right in the browser, and keep what you want in a local library on your own device.
- Safe previews. Received pages and scripts are shown, never run.
- A library in this browser, to save or send again later.
- Nothing online. Clear it whenever you like.
Features
Everything a parcel needs on the way
Built for real files: big videos, deep folders, flaky Wi-Fi and phones that fall asleep.
Text and links
Send a note or a link to your other device, like a shared clipboard. Texts typed while offline go out on the next connection.
Known devices
Paired once? Next time pick the device and type only the confirmation words. Forget it whenever you like.
No relay option
For networks that block the relays, an advanced option connects by scanning a QR code each way, or by pasting the codes.
Whole folders
The tree arrives intact. Incoming paths are sanitized, so nothing lands outside the folder you pick.
Resume after a drop
Reconnect and the transfer continues from the last confirmed chunk instead of starting over.
Two way sync
Two way, push or pull. You review the plan of changes before anything is written.
SHA-256 checked
Every file is hashed while it streams and verified by the receiver before it is marked done.
Confirm with six words
After pairing, type the six words shown on the other screen. A device that only saw your code gets different ones.
Optional passphrase
PBKDF2 with 600,000 rounds to an AES-GCM key on each device. Every chunk is sealed again.
Safe previews
Photos, video, audio, PDF and text, drawn so a received page or script never runs.
Local library
Keep received files in this browser on your own device, to save or send again later.
Installable, offline
Install it as an app. Once loaded, it opens without internet.
Help on strict networks
When a direct route is blocked, filefinch explains why and lets you add your own TURN relay.
0servers of ours
0accounts to create
600,000PBKDF2 rounds for a passphrase
2,048words in the handshake list
Device scenarios
Any device to any device
filefinch runs in the browser, so the pair can be anything with a modern browser.
Photos from your phone to your PC, no cable
- Open filefinch on the PC. Six words and a QR code appear side by side.
- Type the six words on the phone, or scan the QR code with its camera.
- Type the confirmation words, then pick the photos and videos.
Videos arrive in their original quality and size. Nothing is recompressed.
Start sending
Two approaches
Cloud upload or direct flight?
Both are useful. Uploading to storage is great when the receiver is offline. A direct transfer is better when you want the file on your other device now, privately and without limits.
| Upload to cloud storage | Direct with filefinch | |
|---|---|---|
| Where your files go | Uploaded to a storage service, then downloaded | Straight from one device to the other |
| Waiting time | Upload first, then the download can start | The receiver gets data as soon as it is sent |
| Account | Usually needed, at least for large files | None |
| Size limits | Set by the plan you are on | None set by filefinch |
| Copies left online | Until you delete them or they expire | None, nothing is stored online |
| Who can read the files | The service can, unless it offers client side encryption | Only the two devices (DTLS, plus an optional passphrase) |
| Both devices online | Not needed, the receiver can download later | Needed while the files fly |
| Works without internet | No | Yes, with the no relay option on the same local network |
Limits, honestly
What a direct flight needs
No middle storage means a few rules of the air. Here they are, before you find out the hard way.
- Both devices must be online
- There is no mailbox in the middle. Keep filefinch open on both devices until the transfer finishes. If one side drops, resume picks it up later.
- Strict networks can block a direct route
- When both devices sit behind strict NAT (common on some mobile carriers and office networks), a direct connection may be impossible. filefinch says so and offers a TURN relay setting. A relay forwards only encrypted packets.
- The 6 words need a public relay to answer
- The word handshake travels through public MQTT relays. If none answers, the advanced no relay option still works.
- Speed follows the slower side
- A direct connection is as fast as the slower of the two links. On the same Wi-Fi that is usually far faster than any upload; across the internet it depends on the upload speed of the sender.
- Phones sleep
- Mobile browsers may pause a tab in the background. Keep the screen on for long transfers, or let resume continue when you come back.
FAQ
Questions people ask
Is filefinch really free?
Yes. It is free and open source under the MIT license. There are no plans, no ads, no account and no tracking. Since there is no server of ours carrying your files, there is nothing to pay for.
How do the 6 words work?
The first device shows six words from a list of 2048 simple English words, plus a QR code that holds the same words. Type them on the other device: the first four letters of each word are enough. The short handshake the two browsers need to find each other travels encrypted through public relays that cannot read it. The code works once and expires in 10 minutes. Once the devices meet, one shows six new confirmation words to type on the other, so a device that only saw your code cannot join. Your files then go straight from device to device.
Do my files go through a server?
No. Files travel over a direct WebRTC connection between your two browsers. The 6 word handshake passes through public relays as ciphertext, and when both networks block direct routes a TURN relay can forward the encrypted traffic. No server of ours is ever involved.
What if a network blocks the relays?
Open Options and choose Connect with no relays (advanced). Each device shows a QR code: scan one each way, or copy and paste the codes. Nothing passes through a relay. Like every mode, the browsers still ask a public STUN server for their public address.
Is there a file size limit?
filefinch sets none. Files are read and sent in 64 KiB chunks and written to disk as they arrive, so a 50 GB video works like a photo. The real limits are free space on the receiving device and both devices staying connected.
Do both devices need to be online at the same time?
Yes. There is no storage in the middle, so the sender and the receiver must both have filefinch open while the files fly. If one closes the tab, the transfer can resume when you reconnect.
Can I send a whole folder?
Yes. Pick or drop a folder and filefinch sends every file with its relative path. In browsers with folder access the tree is written straight into a folder you pick; elsewhere the folder arrives as one streamed .zip download.
Does it work between Android and iPhone, or Windows and Mac?
Yes. filefinch runs in the browser, so any pair of modern browsers can connect: Android to iPhone, Windows to Mac, phone to PC or laptop to laptop.
What happens if the connection fails?
Usually one network is very strict (symmetric NAT or a corporate firewall). filefinch detects the failed connection, explains it in plain words and offers the TURN setting. Trying another network, like a phone hotspot, often works too.
Does filefinch work without internet?
Once loaded or installed, the app opens offline, and the advanced no relay option can connect two devices on the same local network. Pairing with 6 words needs internet to reach the public relays.
Guides
Guides
Short guides to the main things filefinch does.
Your files, on a direct flight.
Open filefinch on two devices and send your first file in under a minute. Free, open source, no account.
