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Frequently asked questions
StrongFolder is free, needs no account and sets no file size limit. Files go directly from the sender's browser to the recipient's over an encrypted WebRTC connection and are never stored on a server. Folders keep their structure. The one rule: the sender keeps the tab open until the download finishes.
Frequently asked questions
Basics
What is StrongFolder?
A free tool for sending files and whole folders directly from one browser to another. It works as a web app at strongfolder.com and as a Chrome extension.
Is StrongFolder free?
Yes. StrongFolder is free. There are no paid plans at the moment — every feature is available to everyone. No account needed to send or receive. Signing in with Google is optional and keeps a list of your transfers.
Does the recipient need an account or an app?
No. They open the link in a browser and download.
Can several people download from one link?
One link can be opened by several recipients; each downloads directly from the sender.
Size and speed
Is there a file size limit?
No size limit set by StrongFolder. The practical limits are free disk space on the recipient's device, connection speed, and how long both devices stay online.
How fast is a transfer?
As fast as the slower connection — usually the sender's upload speed. At 50 Mbit/s upload, 10 GB takes about 27 minutes. See the table in How it works.
Why do I have to keep my tab open?
The sender's browser tab must stay open and online until the recipient finishes downloading — files come from the sender's device, not from a server. See Why the sender must stay online.
Does it work on a phone?
Yes, in a mobile browser. Keep the StrongFolder tab on screen during the transfer — phones pause background tabs. Use the QR code to send from a computer to a phone.
Folders
Can I send a folder without zipping it?
Yes. Folders are sent as folders: subfolders and file names are kept, nothing is zipped. Guide: Send a folder without zipping.
What does the recipient need to save a whole folder?
Saving a whole folder with its structure uses the File System Access API: Chrome, Edge, Opera and other Chromium browsers on a computer. Other browsers can download the files one by one or as a ZIP.
Privacy and security
Are my files stored on your servers?
No. Files are never uploaded to or stored on a StrongFolder server. To create the link, the service keeps transfer metadata: file and folder names, sizes and the number of files.
Is the transfer encrypted?
WebRTC encrypts every data channel with DTLS, so the file stream is encrypted in transit on every connection.
Do files ever pass through your servers?
If a direct connection is impossible (strict corporate firewall, some mobile networks), the encrypted stream passes through a StrongFolder relay (TURN) server. The relay forwards the data and does not store it.
Is StrongFolder like BitTorrent?
No. It is a private connection between your browser and the people who have your link — not a public file-sharing network.
Troubleshooting
The download does not start. What can I do?
Check that the sender's tab is still open and online, refresh the link page, and try another network if you are on a strict corporate or public Wi-Fi network that blocks WebRTC.
The transfer stopped halfway.
Usually the sender's computer went to sleep or the tab was closed. Keep the computer awake and start the download again while the sender is sharing.
How do I contact support?
Write to info@strongfolder.com.
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Send your next file — or folder — directly
No upload, no size limit set by us, no account. Pick a file or a whole folder, copy the link, and the recipient downloads straight from your device.