> ## Documentation Index
> Fetch the complete documentation index at: https://shareclick.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# File transfer

> Send files between your machines over ShareClick's reliable, chunked, resumable-by-offset transfer channel.

Once two machines are connected, the clipboard syncs automatically and you can
send files across the **bulk channel** (TCP) — the reliable side of ShareClick's
[dual-channel design](/concepts/architecture).

## Send a file

```bash theme={null}
shareclick send-file 192.168.1.20:24800 ./report.pdf
```

The file lands in `./received/` on the peer. Use the **other** machine's
`IP:port`.

<Steps>
  <Step title="Connect both machines">
    Start the server and client as usual (see [Usage](/usage)). The clipboard
    starts syncing immediately.
  </Step>

  <Step title="Run send-file">
    From either machine, run `send-file` pointing at the peer's `IP:port` and the
    path to the file.
  </Step>

  <Step title="Find it in ./received">
    On the receiving machine, look in the `received/` directory next to where
    ShareClick runs.
  </Step>
</Steps>

## How it works

A file transfer is three kinds of message on the bulk channel:

1. **`FileBegin`** — announces the file id, name, and size.
2. **`FileChunk`** — many 64 KiB chunks, each written at its `offset`.
3. **`FileEnd`** — signals completion.

Because every chunk carries its byte `offset`, transfers are robust and
resumable-in-principle. See the [wire protocol](/concepts/protocol#bulk-channel)
for the exact message shapes.

<Note>
  The receiver **sanitizes the filename** (strips path components) to prevent
  path-traversal attacks, and writes only into `./received/`. Max frame size is
  64 MiB to guard against a hostile peer forcing a huge allocation.
</Note>

## Clipboard sync

Clipboard sharing needs no command — it's on whenever two machines are
connected. Both **text** and **images** (raw RGBA) sync in both directions over
the same reliable channel.

## Next

<CardGroup cols={2}>
  <Card title="Wire protocol" icon="network-wired" href="/concepts/protocol">
    The exact bulk-channel message formats.
  </Card>

  <Card title="Security" icon="shield-halved" href="/concepts/security">
    How file and clipboard data stay encrypted.
  </Card>
</CardGroup>