Starts with SSH
It logs in with your normal SSH access and starts its own receiver on the far host. No daemon to install, no new accounts.
File transfer for long, lossy networks
Far is fast now.
Send huge files across the world at full speed, even over bad networks.
farwing cp big.iso user@sydney:/data/Free for any use. No limit on copies at once, up to 1 Gbit/s in total unless a license file raises it. A higher --max-rate does not. Farwing Server goes to 10 Gbit/s and beyond.
11.3 Gbit/s
Oregon to Sydney through 1% packet loss
4.1 s
to copy 1 GiB on that path. scp stalled before a complete file.
8.0×
faster than TCP BBR at 1% loss, and ahead of 8 parallel BBR streams
11.5 Gbit/s
the whole path with no loss added, on about 2 of 16 CPU cores
TCP thinks a lost packet means a full road. On a long path, it usually doesn't.
A long path loses packets for ordinary reasons. An ocean cable, a satellite hop, a cross-country land route, a busy exchange, old hardware. That loss is not a full road. Standard TCP backs off every time, and the longer the delay, the longer it takes to speed up again.
Farwing does not slow down for that loss. It watches one thing: whether a queue is building in the network. If the delay grows, it eases off. If not, it keeps the link full and sends the missing blocks again, lowest first. The rougher the path — more delay, more loss — the further standard copy tools fall behind.
Measured, not modeled
Across the Pacific, at every loss level.
Oregon to Sydney, 139 ms round trip. 20-second runs, median of three. Useful data delivered per second, in Mbit/s. This is the ocean path we measure. A satellite hop or a long overland path with the same delay and loss is the same problem: the rougher that road, the wider the gap against standard tools.
Farwing8 × TCP BBR streamsTCP BBRTCP CUBIC (Linux default)
Noneloss
11,498 Farwing
10,828 8 × BBR
4,152 BBR
3,249 CUBIC
0.1%loss
11,431 Farwing
9,945 8 × BBR
1,776 BBR
12 CUBIC
1%loss
11,274 Farwing
8,993 8 × BBR
1,403 BBR
1.5 CUBIC
3%loss
11,015 Farwing
8,028 8 × BBR
491 BBR
0.6 CUBIC
Every speed claim is measured. See how.
Median of three runs, on the same hosts and path for every tool. Loss is added on the sending side; TCP was tuned for this path.All results and method
One gigabyte across the Pacific. About five seconds.
A real 1 GiB copy, Oregon to Sydney, timed from the start of the command to a checked file on disk, against HTTP, UDT, Tsunami, and scp on the same path. Each run had 5 minutes to finish. Oceans are the long case we time most often. Satellite links and cross-continent land paths are the same kind of road, and standard tools fall further behind as the delay and the loss go up.
Farwing times are repeat copies to the same host. The benchmarks page also times a first copy to a new host, with putting Farwing there.
No added loss
Farwing
2.3 s
HTTP
4.0 s
UDT
23 s
Tsunami
5.0 s
scp
82 s
0.1% loss
Farwing
2.3 s
HTTP
stalled
UDT
68 s
Tsunami
91 s
scp
stalled
1% loss
Farwing
4.1 s
HTTP
stalled
UDT
266 s
Tsunami
stalled
scp
stalled
3% loss
Farwing
4.7 s
HTTP
stalled
UDT
stalled
Tsunami
stalled
scp
stalled
Bars on a 5-minute scale. Median of three runs, on the same hosts and path for every tool. Stalled means the copy was still running, had errored, or had made no progress when that limit ended.
Transfer calculator
How long will your copy take?
Pick a file, a link and two places on the map. The estimate comes from our own measured runs: Farwing against the standard TCP that most copy tools use, or against scp.
How it works
Works like scp. Flies like nothing else.
Encrypted end to end
Every session gets fresh keys. Every packet is encrypted and checked with AES-256-GCM. The secret travels inside the SSH session.
Ignores random loss
It slows down only when the delay grows, which means a router queue is filling. It keeps that queue to a few milliseconds.
Finds a way through
UDP blocked? It moves to eight parallel TCP streams. TCP blocked too? It goes through SSH. Same command, same encryption.
Picks up where it stopped
If a copy breaks, run the same command again. Farwing skips the blocks already on disk, on every route, both directions.
Checked as it lands
The whole file is checked with BLAKE3 while it is written, in any order. The check ends milliseconds after the last block. Until then the file keeps a temporary name.
Four lanes, one copy
One copy runs as four coupled lanes, each on its own CPU core. Together they pass per-flow speed limits. At 11.5 Gbit/s, all four together kept about 2 of 16 cores busy.
Remembers the path
Each copy records what the path carried. The next copy to that host starts near full speed, not from zero.
Fast. You set the manners.
On a path of its own, Farwing takes all of it. On a link you share, you choose how much it takes.
One flag picks the manners for a copy. Farwing Server sets the same limits for each person and group.
Products
One engine. Three ways to fly.
For engineersFree
Farwing
scp-style copies from the terminal. As many at once as you need, sharing 1 Gbit/s in total on each machine. A licensed Farwing Server at the far end sets its own speed.
- Any use, including commercial
- No limit on copies at once
- 1 Gbit/s in total, unless a license file raises it
- Linux, macOS and Windows
For people who receive filesFree
Farwing Desktop
Opens when you click a Farwing link. A licensed Farwing Server sets the speed of its transfers, and every file shows as verified.
- No account, no setup
- Pause, resume, retry
- Windows, macOS and Linux
For teamsFrom $3,600 a year
Farwing Server
A web portal on your own server for sending, receiving and automating transfers.
- Packages, shared folders, guests
- Hot folders, sync, S3 and the API on every paid plan
- Free mode for 5 users, no license needed
Quick start
Three commands to the other side.
Install Farwing on both hosts. You need an SSH login to the far host. For full speed, let the far host accept UDP on port 47700. If it does not, Farwing finds another route.
1 Install it
curl -fsSL -o farwing-install.sh https://dev.farwing.io/install.sh bash ./farwing-install.sh --version dev2 Copy a file, the way scp does
farwing cp big.iso user@host:/data/3 Test the path, no disk used
farwing bench user@host --size 5G
Your files. The far side. Full speed.
Start free from the terminal, or run Farwing Server for your whole team. Every server can start a 30-day trial with every feature, from its own license page.