Question 1

What is FileFly and how does it work?

Accepted Answer

FileFly is a desktop app that moves files directly between devices on the same Wi-Fi or local network (LAN). There is no cloud, no relay server, and no account — files travel peer-to-peer straight from one device to another, so transfers are as fast as your network hardware allows.

Question 2

Which platforms are supported?

Accepted Answer

FileFly runs on Windows 10 and 11, macOS, and Linux. You can install it from the Microsoft Store, the Mac App Store, or via Snap on Linux. Devices on different operating systems can transfer to each other freely.

Question 3

How do I send my first file?

Accepted Answer

Install and open FileFly on both devices and make sure they're on the same network. The other device appears under Available Devices. Drag a file onto it (or select the device and choose a file), then ask the person on the receiving device to accept the incoming transfer. That's it.

Question 4

Do I need an internet connection or an account?

Accepted Answer

No. FileFly never asks you to create an account or sign in, and it doesn't use the internet to move your files. It only needs both devices to be on the same local network.

Question 5

My other device isn't showing up. What should I check?

Accepted Answer

Work through this checklist — most cases are one of these: FileFly is open on both devices. Both devices are on the same Wi-Fi network (not one on guest Wi-Fi and one on the main network). Your firewall is allowing FileFly on port 23013 (see the firewall question below). Any active VPN is turned off — VPNs route traffic away from your local network. Client / AP isolation is disabled on your router (common on guest and public networks — it blocks devices from seeing each other). Press the refresh button to re-scan for devices.

Question 6

Why does FileFly need to go through my firewall?

Accepted Answer

FileFly listens on port 23013 for both device discovery and file transfers. If your firewall blocks it, devices won't find each other or won't be able to receive files. The first time you run it, allow FileFly when your operating system prompts you. On Windows, allow it for Private networks; on macOS, allow incoming connections if prompted; on Linux, make sure port 23013 isn't blocked by your firewall (e.g. ufw).

Question 7

Can I transfer between two different Wi-Fi networks or over the internet?

Accepted Answer

No. FileFly is designed for devices on the same local network. Both devices need to be on the same Wi-Fi or LAN subnet so they can reach each other directly. It does not transfer over the internet.

Question 8

Does it work over Ethernet or a mix of wired and wireless?

Accepted Answer

Yes. Wired, wireless, or a mix all work as long as the devices are on the same network subnet (for example, all connected to the same router).

Question 9

Why does the other person have to approve the transfer?

Accepted Answer

Every transfer is consent-based for your safety. When you send a file, the receiving device shows an Incoming File Transfer prompt, and the person must accept before anything is sent. If they deny it (or don't respond), nothing is transferred.

Question 10

Where do received files get saved?

Accepted Answer

Incoming files are saved to your download location, which you can see and change under Settings → Download Location. On macOS you may be asked to grant access to the folder you choose the first time — that's expected.

Question 11

Is there a file size limit? Can I send folders?

Accepted Answer

There's no built-in size cap, so large files transfer fine — the practical limit is the free disk space on the receiving device. You can send individual files; for many items, compress them into a single archive first.

Question 12

A transfer failed or got stuck partway. What now?

Accepted Answer

Usually one of these: The receiver didn't accept the prompt in time, or it was dismissed — start the transfer again. One device went to sleep or dropped off Wi-Fi — keep both awake and connected, then retry. The receiving device ran out of disk space — free up space and resend.

Question 13

Are my files private? Does FileFly upload them anywhere?

Accepted Answer

Your files never leave your local network and are never uploaded to a cloud or third-party server — they move directly between your devices. FileFly collects no user data or telemetry while transferring. For full details, see our Privacy Policy.

Question 14

What does “Device Key Changed” mean?

Accepted Answer

Each device has its own identity key, and FileFly remembers (“pins”) it the first time you connect. If a device later presents a different key, you'll see a Device Key Changed prompt. This almost always means FileFly was reinstalled or reset on that device. If you trust the device, approve the new key; if you weren't expecting it, reject it.

Question 15

What is a trusted device, and how do I reset trust?

Accepted Answer

A trusted device is one whose identity key FileFly has already pinned, so you aren't prompted again on every connection. To start fresh, go to Settings → Clear Trusted Devices. You'll then be asked to re-trust each device the next time it connects.

Question 16

How do I rename my device?

Accepted Answer

Open Settings → Device Name and enter a new name. This is the name other people see for your device in their Available Devices list, so pick something recognizable like “Alex's MacBook”.

Question 17

How do I change where files are saved?

Accepted Answer

Go to Settings → Download Location and choose Change to pick a new folder.

Question 18

Can I change the language?

Accepted Answer

Yes. FileFly is available in 10 languages — English, Spanish, French, German, Italian, Dutch, Arabic, Hindi, Malayalam, and Chinese. Choose one under Settings → Language.

Question 19

How do I clear my transfer history?

Accepted Answer

Use Settings → Clear Transfer History. This removes the list of recent transfers shown in the app; it does not delete any files you've already received.

Question 20

Devices can't see each other even though they're on the same Wi-Fi.

Accepted Answer

This is almost always your network or firewall. Disable client/AP isolation on the router, turn off any VPN, and make sure FileFly is allowed through the firewall on port 23013. Guest and public networks frequently isolate devices and won't work. Restarting FileFly on both devices after changing these settings helps.

Question 21

I see an error about the receiver detecting a key change.

Accepted Answer

This means the receiving device no longer recognizes your identity key (often after a reinstall). Ask the person on the receiving device to approve the new key when prompted, then try the transfer again.

Question 22

The app never shows an incoming-file prompt.

Accepted Answer

The receiving device usually isn't reachable on port 23013 — its firewall is blocking inbound connections. Allow FileFly through the firewall on that device (Private networks on Windows), then resend.

Question 23

Nothing here fixed it — how do I get help?

Accepted Answer

Email me at amal@fileflyapp.com with your operating system, FileFly version, and a description of what happens. The more detail, the faster I can help.

Help & Support

Getting Started

Connecting & Discovery

Sending & Receiving Files

Trust & Privacy

Settings & Customisation

Troubleshooting

Still need a hand?