Why Windows warns about this download
Fast Media Sorter & Sharing for Windows is a free program written by one independent developer. The builds published on GitHub, which winget installs too, are not code-signed, so Windows treats them with extra caution and you may meet a warning or two. Below is what each one is, why it appears, exactly what to click, and what the program never does.
What the warning is
One of these three, depending on what you downloaded.
- «Windows protected your PC» - this is SmartScreen. It appears the first time you run a setup file or the program from the portable ZIP.
- «Do you want to allow this app to make changes to your device?» - this is the Windows administrator prompt. It appears only if you choose to install for all users or switch folder sharing on, and the fourth section says exactly what each does with it.
- An antivirus warning about the single-file download, which only releases before 12 June 2026 offered. Microsoft Defender scores its self-extracting bootstrap as Program:Script/Wacapew.A!ml - a known false positive for this shape of file. The setup files and the portable ZIP are not affected.
Why it appears
Nothing is broken and the warning is not a mistake. SmartScreen asks two things about a file: is it signed with a certificate Windows recognizes, and have enough people already run it.
- Not signed. A code-signing certificate costs several hundred dollars a year. The program is free and earns nothing, so paying for one is a choice that has not been made - it is not an oversight.
- Not yet known. Reputation is counted per file, so every new version starts from zero. It builds up on its own as people download that release, which is why the warning fades between versions and comes back for a while after each new one.
- The Microsoft Store build is the exception: Microsoft signs it during certification, so it shows none of this. It is the same program.
Exactly what to click
Two clicks, and nothing here weakens your protection.
- SmartScreen: click More info on the dialog, then Run anyway. That is all.
- Administrator prompt: read the next section first, then answer Yes. Answer No to the folder-sharing prompt and the program still installs and runs in full - only sharing stays off. Setup itself needs the prompt only if you chose to install for all users.
- Antivirus: if the file was quarantined, restore it and add an exception for that one install folder. Never switch SmartScreen off and never disable your antivirus - neither is needed here, and both keep protecting everything else you download.
- If you would rather verify than trust: every release carries a .sha256 file beside it, and Get-FileHash <file> -Algorithm SHA256 in PowerShell must print the same value. The source code is public.
What administrator rights are used for, and how to take them back
The viewer itself never asks for administrator rights. Setup asks only if you choose to install for all users, and folder sharing only when you switch it on. Each use is listed here, then the way back.
- Installing for all users - your choice in Setup. Setup first asks whether to install for you only, which needs no administrator rights, or for every account on this PC. Only the second asks Windows, to put the program in Program Files and its shortcuts where every account sees them.
- Folder sharing - one firewall rule. When you switch sharing on, in Setup or later in the Share Manager, Windows asks once and a single inbound firewall rule is added for companion\fms-share-worker.exe. It lets that one program receive connections and does nothing else. Until you switch sharing on, nothing listens and nothing is added.
- Always-on sharing - a Windows service. Only if you ask for it, in one of two ways: in the Share Manager's «Manager settings», Hosting, «Switch sharing to a Windows service..», or with the separate Server installer, which you download and run yourself. Windows asks once, and four things are done: the service FastMediaSorterCompanionSFTP is registered and runs as LOCAL SERVICE; the firewall rule is pointed at the copy of the sharing program the service runs; LOCAL SERVICE may read each folder you share, and write only where you allowed writing; and the sharing settings, password and host key move to %ProgramData%\FastMediaSorterCompanion, a folder only administrators, the service and your account can open.
- To take it back without uninstalling, open the Share Manager's «Manager settings»: Network, «Switch off server features..» removes the firewall rule; Hosting, «Remove the server role» stops and deletes the service, takes back its folder permissions and removes the firewall rule; Hosting, «Return to the User edition..» also removes the service and the folder permissions, but hands sharing back to your own session with its firewall rule. Each asks Windows once.
- Or uninstall: each entry in Windows Settings, Apps removes what it added. This program is listed there as FastMediaSorter LITE (the name it was first published under) and the Server edition as Fast Media Sorter Folder Share Server. FastMediaSorter LITE removes its firewall rule - installed for you only, Windows asks once for that - and offers to remove a service its Share Manager registered. Fast Media Sorter Folder Share Server removes its service, the folder permissions and the firewall rule. A silent uninstall, such as winget uninstall, cannot ask, so it leaves a Share Manager service in place, and for an install made for you only the firewall rule too; switch them off in the Share Manager first.
- Kept on purpose: the host key, password and folder list stay in %LOCALAPPDATA%\FastMediaSorterCompanion - or in %ProgramData%\FastMediaSorterCompanion once sharing has run as a service - so paired phones reconnect after a reinstall. Delete that folder and every phone has to be paired again.
What the program never does
The same list as the privacy page and the Microsoft Store data-safety answers, because there is only one truth to tell.
- No telemetry, no analytics, no accounts, no advertising. The developer receives nothing about you or about how you use the program - unless you press «Send the logs to the author», which opens a message in your own mail program for you to check and send yourself.
- It never sends your files anywhere by itself. When you share folders, your phone connects straight to your PC over an encrypted SFTP connection.
- It never opens a port and never asks for administrator rights on its own. Sharing is off until you switch it on, and the window always shows what is reachable and from where.
- It downloads something only when you ask or say yes to a prompt that names what is being fetched: an OCR language pack, the OCR or video playback runtime, the video encoder FFmpeg, the Ollama installer or a translation model for it, or doc-html-translate through winget. Nothing about your files is sent with the request.
- Text you translate goes only to the translation endpoint you set up yourself - a model on your own machine, or a server you named.
One third-party service can be contacted, and only if you turn on internet access for sharing: check-host.net is asked to confirm that your forwarded port answers from outside, which shows that service your public address and port. Nothing else is sent to it. Two more things stay inside your own network: with internet access on, the program asks your router to forward the sharing port (UPnP or NAT-PMP), and while sharing runs, the PC announces itself on the local network (mDNS) so a paired phone can find it again.
Opening a page of this website, as opposed to using the program, contacts up to three outside addresses: fonts.googleapis.com and fonts.gstatic.com (Google Fonts, for the lettering of the pages) and, on the home page and its language versions, api.github.com (GitHub, to look up the latest release for the download link). Each receives your IP address and your browser's user agent and nothing else. No analytics, tag-manager or advertising address is contacted. The privacy page says the same.