SpeedBand
Diagnose whether your LAN is stable enough for realtime streaming. Measures latency, jitter and low-percentile throughput via browser - no install on the second device, no telemetry.
Table of contents
What SpeedBand does
Runs a small HTTP server on your machine. Another device opens the page in a browser and runs a full test sequence:
- Latency and jitter (
/api/ping)
- HTTP download throughput (
/api/download)
- HTTP upload throughput (
/api/upload)
- WebSocket realtime bitrate ladder (
/api/ws)
All traffic stays inside the LAN. Results include a stable bitrate range with headroom levels, a quality label and a bitrate ladder breakdown.
Peak speed is not a safe streaming bitrate. SpeedBand uses low-percentile throughput, jitter and stall detection to estimate a safe operating range.
Why not iperf3?
iperf3 requires installation on both devices and reports raw TCP throughput - not what matters for streaming.
SpeedBand runs as a single binary or go run. The second device only needs a browser. It measures what streaming actually uses: low-percentile throughput, jitter, stall detection and realtime bitrate stability across a stepped ladder. The output is a safe bitrate range with headroom levels, not just a peak number.
Use cases
- Game and VR streaming (Moonlight/Sunshine, Steam Link, Air Link, Virtual Desktop, ALVR)
- NAS and media transfer checks
- Wi-Fi diagnostics
- LAN testing between PC, phone, tablet, laptop, headset or Steam Deck
- Finding whether peak throughput hides jitter, stalls or unstable low-percentile results
Results
Quick start
Download the binary for your platform from the Releases page and run it.
Linux:
chmod +x speedband-linux-amd64
./speedband-linux-amd64
macOS:
chmod +x speedband-macos-arm64 # Apple Silicon
./speedband-macos-arm64
chmod +x speedband-macos-amd64 # Intel Macs:
./speedband-macos-amd64
Open the LAN URL printed in the terminal on any device in the same network.
Build from source
Windows:
go build -o speedband.exe ./cmd/speedband
Linux / macOS:
go build -o speedband ./cmd/speedband
Flags
| Flag |
Default |
Description |
--host |
0.0.0.0 |
Listen address |
--port |
8080 |
Listen port |
--open |
false |
Auto-open browser on start |
--debug |
false |
Verbose logging |
Firewall
If the page does not open from another device:
- Confirm both devices are on the same subnet.
- Windows: when prompted, allow access on Private networks. If not prompted, allow
speedband.exe or go.exe in Windows Firewall for Private networks.
- Linux: ensure the port is open (
sudo ufw allow 8080/tcp for UFW-based distros).
- macOS: allow incoming connections when prompted by the OS firewall dialog.
- Try the numeric IP instead of
.local.
- Disable VPN temporarily.
SpeedBand listens on 0.0.0.0 by default. Run it only on a trusted local network.
Reading results
Bitrate range levels:
| Level |
Meaning |
| Very safe |
Conservative estimate with extra headroom |
| Recommended |
Practical stable operating range |
| Risky upper |
May work; showed reduced headroom or spikes |
| Avoid |
Not recommended without real-app validation |
Quality labels:
| Label |
Meaning |
| Excellent |
Strong low-percentile throughput, low jitter |
| Good |
Suitable for most realtime tasks |
| Acceptable |
Usable; leave headroom |
| Risky |
Unstable enough to require caution |
| Unstable |
Not suitable for high bitrate realtime use |
Reports
- Download JSON - saves report on the client device.
- Save to server - sends report to the machine; saves a
.log file in reports/ under the server working directory.
Recommended test conditions
- Connect the PC to the router with Ethernet.
- Use 5 GHz or 6 GHz Wi-Fi for the second device.
- Close active downloads, cloud sync and game updates.
- Run the Full stability test before choosing a high bitrate.
- Repeat 2–3 times; trust the more conservative result.
License
MIT
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