Open Files → Local transfer on both devices. Give each device a recognizable name, choose its receive folder, and select Enable local transfer. The session lasts one hour; Stop sharing ends it immediately and cancels unfinished jobs. The workbench controls require a direct loopback browser connection.
- Select the receiving device under Choose a device.
- Compare its full fingerprint with the receiver's Connection details. Names
and discovery announcements are self-reported, not authenticated identities.
- Choose up to 32 files, then send. The receiver accepts or declines each file.
- Watch progress and average speed. Completed sends include a SHA-256 match
against the receiver's streamed digest. Incoming files show their saved path.
Files stream directly over TLS 1.3 without staging the whole file in memory or using the Downloader/aria2 engine. There is no bandwidth throttle. The network, VPN route, encryption, and storage determine throughput; unlimited speed is not possible. Four transfers may be active, and the session retains 64 recent jobs.
LAN discovery and private networks
Nearby discovery uses IPv4 multicast 224.0.0.168:53318; transfers use TCP 53318. Allow those ports for ProtoPeek on the intended network if the firewall blocks them. Guest Wi-Fi isolation and multicast filtering can prevent discovery. ProtoPeek discovers participating transfer devices, not people or every LAN host.
For a VPN or discovery failure, open the receiver's Connection details and copy a reachable IP:port#fingerprint connection. Paste it into Connect by address / VPN on the sender. IPv6 uses [address]:53318#fingerprint. Installed Tailscale devices are available under Extensions → Tailscale in the v0.7.0 layout. Earlier releases placed that workbench under Network.
Both devices need this ProtoPeek implementation. Existing Tailscale or WireGuard routes can carry it, subject to their firewall and access policy. Multicast usually does not cross those routes. ProtoPeek does not set up a VPN, punch through NAT, or provide a relay. This is independent of Tailscale Taildrop and is not a LocalSend-compatible client. LocalSend's protocol informed the discovery → offer → streaming flow; the implementation is native Go.
Storage, cancellation, and identity
The receiver accepts metadata before any file is saved. A single-use random token authorizes that file's upload; unsolicited uploads are refused. Offers expire in two minutes. TLS certificates are temporary and change when sharing restarts; sender connections pin the selected fingerprint and reject changed certificates.
Files are written to private temporary files inside the chosen folder, flushed, and published without overwriting an existing file. Collisions receive a suffix. On filesystems without hard-link support, the file goes into a newly reserved ProtoPeek-… subfolder. Paths are confined to the receive directory. Incomplete and cancelled files are removed; already completed files remain. Interrupted transfers restart from the beginning; resuming partial files is not implemented. Closing the sending view cancels its sends. A receiving session remains enabled until stopped or expired; keep its view open to answer incoming offers.
This functionality is included in published v0.7.0. Real two-device LAN discovery and VPN throughput still depend on the actual interfaces, firewalls, and route and should be tested on each deployment.
Development verification
The transport tests use real TLS listeners and real files on the test OS. They cover accepted and empty files, collisions, rejection, cancellation and cleanup, certificate pinning, invalid tokens, path validation, and restart. CI runs these on Windows, Linux, and macOS, plus the Go race detector on Linux.
A single 64 MiB loopback benchmark on the development Windows machine on 15 September 2026 measured 261.85 MB/s with approximately 1.03 MB allocated during the operation (the source buffer was allocated before timing). This is local test evidence, not a LAN/VPN speed promise. Run go test ./internal/localshare -run '^__PP_TOKEN_0__#39; -bench BenchmarkStreamingTransfer -benchtime=1x to measure your machine.
The frontend remains route-lazy, without new package dependencies or an increased startup ceiling. Dedicated feature caps and a measured aggregate allowance keep growth visible; the current production build reports the actual chunk sizes.