What DropBench is for
- Between your own devices: photos from a phone to a computer, a document from a work laptop to a home one, without cables, cloud accounts or messaging yourself.
- Between different systems: Android, iPhone, Windows, macOS, Linux and ChromeOS, in any combination, as long as there is a modern browser.
- Large files: videos, archives and disk images that are too big for email or a messenger.
- Private files: they go straight to the receiver and are never stored anywhere along the way.
Both people need to have the page open at the same time: that is the price of not storing anything on a server.
How to send files
- Open DropBench and choose files, or drag them onto the page. Folders are skipped: zip them or pick the files inside.
- Optionally set a password. The receiver will need to enter it before seeing the list of files.
- Press Create link. You get a link and a QR code.
- Send the link, or let the receiver scan the QR code with the camera of the other device.
- Keep the page open. You see who is connected and the progress and speed of each download. You can add or remove files while sharing.
How to receive files
- Open the link. The browser connects to the sender and shows the list of files.
- Download files one by one, or all at once.
- Files up to 256 MB are kept in memory and then saved like any download. Larger ones are written straight to disk; Chrome and Edge ask you where to save them.
How it works
DropBench uses WebRTC, the same technology browsers use for video calls. The two browsers first find each other through a small public signalling server (PeerJS), which only passes their connection details. After that the file data flows between them directly.
- Encryption: WebRTC always encrypts the connection (DTLS). Nobody between you, including your provider, can read the files.
- Direct or relayed: most of the time the browsers connect directly. If a strict router or a corporate network blocks that, the data goes through a relay (TURN). It stays encrypted, but the transfer may be slower. The page shows which route is used.
- Password: the receiver’s browser sends only a salted SHA-256 hash of the password, never the password itself, and after 5 wrong attempts the connection is closed.
- Many receivers: you can share with several people at once; each one gets their own connection.
Tips for fast, reliable transfers
- Keep the sender’s screen on. DropBench asks the device not to sleep while sharing, but closing the tab or locking a phone stops the transfer. Files already received are safe.
- Use the same Wi-Fi for transfers between your own devices: the data then stays inside your home network and moves at local speed.
- For very large files use Chrome or Edge on the receiving computer: they can write straight to disk, so the file does not have to fit in memory.
- If the connection fails, try another network, for example mobile data instead of a guest Wi-Fi, or ask the sender to create a new link.
Frequently asked questions
Is there a file size limit?
DropBench itself has none. In practice the limit is the receiver’s free disk space and, in browsers that cannot write straight to disk (Safari, Firefox), free memory.
Are my files stored anywhere?
No. They are read from the sender’s disk in small pieces and written on the receiver’s device. DropBench keeps no history, and the link stops working as soon as the sender closes the page.
Can I send files from iPhone to Android or Windows?
Yes. Open DropBench in Safari or Chrome on the iPhone, choose the files, and open the link or QR code on the other device.
Why is the transfer slow?
Speed is limited by the slower of the two connections, usually the sender’s upload. If the page says the transfer goes through a relay, switching networks often gives a direct and faster route.
Is it safe to use on public Wi-Fi?
The connection is encrypted end to end, so other people on the network cannot read the files. For sensitive files, also set a password and share it through a different channel.