rohit267/net-merge

Use all your network adapters at once on Windows. Every new connection (TCP and UDP, IPv4 and IPv6) is pinned to one adapter (Wi-Fi, Ethernet, USB tether, phone hotspot), so many parallel connections (browsers, Steam, updates, downloads) run over all your links at the same time. A single connection is still limited to one link.

Measured with Wi-Fi + an Android USB tether + an iPhone hotspot, 9 parallel downloads: 232-303 Mbit/s vs about 121 Mbit/s for the fastest single link.

No server, VPN or account is involved: connections go straight out of the adapter they are assigned to.

• Steam downloads
• Torrent Downloads
• Large file uploads to Google Drive
• Large file downloads using IDM (If server supports multiple connections)

Download net-merge-setup-x.y.z.exe from the releases page and run it (needs admin). It is not code-signed yet, so SmartScreen will warn: More info > Run anyway. A portable zip is also published.

Then start net-merge from the Start menu. A tray icon appears:

• left-click toggles ON / OFF
• right-click shows live speed per adapter, "Turn on/off", and Quit

Tick Start net-merge when I sign in in the installer (or run net-merge autostart on) to start it at sign-in without a UAC prompt.

net-merge on | off | quit | status | list | autostart on|off|status | version
net-merge tray            tray app (asks for admin once)
net-merge run             system-wide in a console window
net-merge socks           plain SOCKS5 proxy on 127.0.0.1:1080 (no admin, per-app)
net-merge cleanup         remove leftover routes after a crash

Flags for tray/run/socks: -include "WiFi,Ethernet" (only these adapters), -weight "Name=3" (fixed weight instead of measured), -ipv6 auto|on|off, -log file.

• ON creates a Wintun adapter net-merge and two /1 routes per IP family that beat the default route without touching it. OFF deletes them. If the process dies the adapter and routes die with it, so a crash can't leave the machine without internet.
• Flows entering the TUN are terminated in a userland TCP/IP stack (tun2socks/gVisor) and re-dialed from a chosen adapter: the socket is bound to that adapter's source IP and forced out of it with IP_UNICAST_IF, so it can never loop back into the TUN.
• Adapters are detected automatically and re-scanned every 3 s. Only real hardware with a default gateway is used: tunnels, VPNs (Tailscale, WireGuard, ...), virtual switches and LAN-only adapters are skipped (net-merge list shows why).
• Each adapter and each address family is probed for real internet access. A tether with no data or a captive-portal Wi-Fi gets no flows; a recovered link rejoins within seconds.
• Flows go to the adapter with the lowest (active flows + 1) / weight. Weights follow measured throughput, separately for IPv4 and IPv6 (a link can be fast over native IPv6 and slow over translated IPv4).
• IPv6 (-ipv6 auto|on|off, tray checkbox): IPv6 flows can only leave through adapters that have IPv6, and apps that prefer IPv6 (browsers, OBS, curl) would funnel everything onto them. In auto mode IPv6 is balanced only when every adapter has working IPv6; otherwise new IPv6 connections are refused at the SYN (UDP gets ICMP unreachable), apps fall back to IPv4 instantly, and IPv4 spreads over all adapters. Cost: IPv6-only hosts are unreachable while the adapters differ (untick the tray box or use -ipv6 on).

• One connection = one adapter. A single big download won't speed up; many connections will.
• With adapters that differ in IPv6 support, IPv6-only hosts are unreachable in auto mode (see above).
• Sites that tie a login to one IP may see a different IP per connection and ask you to re-verify.
• Needs admin (for the TUN). Windows 10/11, x64 only.

Needs Go (see go.mod) and, for the installer, Inno Setup 6.

go test ./...                       # uses loopback aliases as fake adapters; no second link needed
scripts\build.ps1 -Version 0.1.0    # dist\: net-merge.exe, net-merge-tray.exe, installer, portable zip

wintun.dll is not in the repo: scripts\fetch-wintun.ps1 downloads it and verifies its SHA-256 and its WireGuard LLC signature. To run from source, put it next to the exe:

go build -o net-merge.exe .
scripts\fetch-wintun.ps1 -OutDir .

Releases are built by GitHub Actions when a vX.Y.Z tag is pushed (.github/workflows/release.yml). go test -run xxx -bench Relay ./... measures the relay data path (about 3 GB/s over loopback).

Don't benchmark against speed.cloudflare.com repeatedly: it rate-limits the IP (HTTP 429) after a few large downloads and the numbers become meaningless.

MIT, see LICENSE. Third-party components are listed in THIRD-PARTY-NOTICES.md.