Send files without interruptions, even when the connection drops
KEIBIDROP sends a file straight from one computer to the other, with no upload to a server first. If the connection drops, the part already received stays on disk. When the same peer reconnects, the transfer continues from the last block received and does not start over.
There is no file size limit and no account. It is free, the engine is open source, and it runs on macOS, Windows, Linux and Android.
Resume after a dropped connection
The receiving side keeps a map of the blocks that have arrived. A cut link leaves that map and the received blocks on disk. After the reconnect, only the missing blocks cross the link.
On 3 September 2026 we cut a 40 MB download at 8 MB. After the reconnect it finished, and the checksums matched on both sides. Both peers ran on one Mac and connected through our relay bridge in Timisoara.
Hours-long sessions
In two soak runs of 17 hours in total, between a server in Singapore and one in Timisoara, a fresh 8 MiB file every 10 minutes arrived byte-exact 102 times out of 102, with zero reconnects. The runs used the relay bridge and a July 2026 build.
Key rotation inside the stream
The encryption keys rotate while data flows. In a playback test paced at 40 Mbps, the keys rotated 9 times and the player never ran out of data. The slowest fetch took 171 ms against a budget of 2 seconds.
Open a file during a large transfer
Opening or seeking a file does not wait behind a large background transfer, because urgent reads take their own lane.
Measured
| Test | Result | Conditions |
|---|---|---|
| 40 MB download cut at 8 MB | Finished after the reconnect, checksums matched | Two peers on one Mac, through the relay bridge, 3 Sep 2026 |
| Soak, 17 hours in two runs | 102 of 102 files byte-exact, 0 reconnects | Singapore to Timisoara servers, relay bridge, 8 MiB every 10 minutes |
| Key rotation during playback | 9 rotations, 0 underruns, slowest fetch 171 ms | Playback paced at 40 Mbps, 2 s budget per fetch |
Usage
- Install KEIBIDROP on both computers from the install page.
- Exchange codes once and save the other computer as a contact.
- Drop the file into the window. The other person presses Save.
- If the connection drops, connect again from the contact list. The transfer continues from the last block received.
Both computers must be on and connected for a transfer to move. A transfer stopped by a dropped link continues after the next connect.
For a file you need while the other computer is off, pull a full copy first. The how it works page explains which bytes stay on your disk.
Send large files for free · Send large files without uploading them · Network paths