Running a web radar on a phone or tablet
A web radar server runs on the second PC and sends the radar to a phone browser. Find the PC's LAN address, add a firewall rule, connect the phone, and understand what exposing a local port means.
Short answer
A web radar is an HTTP and WebSocket server on the second PC, open to any browser on your network. It needs no fuser or capture card, just the PC's LAN address, a firewall rule for the port and a device on that network.
On this page10
- How does a web radar work?
- What does a web radar need?
- How to set up a web radar
- Commands to find the address and open the port
- Why a web radar needs no fuser or capture card
- What can't a web radar do?
- Why won't the phone connect?
- Who else can open your web radar?
- What to check before you leave it running
- Common questions about web radars
How does a web radar work?
The radar software on the second PC starts a small web server with two halves. One half serves a page made of HTML, JavaScript and a map image. The other half is a WebSocket endpoint that stays open and pushes position updates as the reader produces them. A browser loads the page once and then receives a stream of coordinates over that socket, which is why the radar moves smoothly without ever reloading. Implementations commonly bind to localhost on a default port, which is port 80 in several published projects. Most of them expose a settings field for the host name or address to bind to.
What does a web radar need?
There are six requirements, and the last one is the main reason to use this path at all.
- A working read path
- The web radar is a second front end on the same reader. If the reader is not resolving the game, no browser will show anything
- The second PC's LAN address
- The address other devices connect to. Usually something in 192.168.x.x or 10.x.x.x
- A bind address that is not localhost
- A server bound to localhost answers only the machine it runs on. Binding to the LAN address, or to all interfaces, is what makes it reachable
- One inbound firewall rule
- Windows Defender Firewall blocks the port by default. One allow rule for that TCP port on the private profile is enough
- The viewing device on the same network
- Same router, same subnet. A phone on mobile data will not reach it, and guest networks are usually isolated from the main one
- Nothing else
- No fuser, no capture device, no second video cable. This path sidesteps the display problem entirely
How to set up a web radar
Get the desktop radar working first, because every step below assumes it already works.
- Confirm that the reader works normally on the second PC and that the desktop radar shows the game
- Find the second PC's LAN address with ipconfig and note the IPv4 address of the active adapter
- In the radar software's web radar settings, set the bind host to that address, or to all interfaces if the option exists, and note the port
- Add an inbound firewall rule for that TCP port on the second PC, scoped to the private network profile
- Open the page on the second PC itself first, at localhost and the port, because if that fails, the problem is the software and not the network
- On the phone, open a browser and enter the second PC's address and port
- Give the phone a fixed place to sit, on a stand beside the monitor, and turn its screen timeout off
- If the socket drops between matches, restart the radar and reload the page, because several published implementations close the socket when a round or raid ends
Commands to find the address and open the port
Run these commands in an elevated Command Prompt on the SECOND PC.
REM Find this machine's LAN address
ipconfig
REM Look for the active adapter's IPv4 Address, e.g. 192.168.1.42
REM Allow the web radar's port inbound, private networks only
netsh advfirewall firewall add rule name="Web radar" dir=in action=allow protocol=TCP localport=8080 profile=private
REM Then open this on the phone, substituting your own address and port
REM http://192.168.1.42:8080
REM Remove the rule when you are done
netsh advfirewall firewall delete rule name="Web radar"Why a web radar needs no fuser or capture card
Both of those boxes exist to solve one problem, which is getting the second PC's picture in front of you. A web radar solves it by not producing a picture on the second PC at all; it produces a page, and any screen with a browser can render it. A phone propped beside the monitor, a tablet, an old laptop and a browser window on a second display all work the same way. There is no video chain, no EDID, no cable order and no shared refresh ceiling, so for a radar-only build it is the cheapest and most robust display path there is.
Info
What can't a web radar do?
A web radar is a map, not an overlay. It cannot draw boxes on the game image because it never touches the game's video path, and that is exactly why it is simple. If you want ESP rendered over the game on your main monitor, network settings cannot give you that, and you are back to a fuser or a capture card.
Why won't the phone connect?
The first two rows cover the large majority of reports.
| Symptom | Likely cause | Fix |
|---|---|---|
| Page loads on the second PC but not on the phone | The server is bound to localhost, so it answers only its own machine | Change the bind host to the LAN address, or to all interfaces, then restart the radar |
| Connection times out from the phone | Windows Defender Firewall is dropping the inbound connection | Add an inbound TCP allow rule for that port, and confirm the network is classified Private rather than Public |
| Connection refused immediately | Nothing is listening on that port — wrong port, or the server is not running | Re-check the port in the software's settings and confirm the web radar feature is actually enabled |
| Phone is on Wi-Fi but still cannot reach it | Guest network or client isolation on the router, or the phone is on a segregated subnet | Put the phone on the same network as the second PC and disable client isolation for that network |
| Page loads, map is empty | The page is served but the WebSocket is delivering nothing, or the reader is not in a match | Check the reader first, because if the desktop radar is empty too, this is not a network problem |
| Radar freezes at the end of every round | Several implementations close the socket when the match ends | Restart the radar and reload the page. This is documented behaviour, not a fault |
| Smooth on the PC, stuttery on the phone | Wi-Fi quality, or an update interval that floods a weak link | Move to 5 GHz or closer to the router, then raise the update interval until it is stable |
Warning
Who else can open your web radar?
You are running an unauthenticated web server on your own machine, so anything on the same network that knows or guesses the address and port can open the radar. That includes flatmates, guests on the same Wi-Fi and anything else connected to it. Several published projects go further and tell you to forward the port on your router so that friends can connect. Understand what that means before you do it. A forwarded port is reachable from the open internet, and the traffic is plain HTTP unless you put something in front of it. The listening service is also the same code that is reading your game. Keep it on the LAN, keep the firewall rule scoped to the private profile, and remove the rule when you stop using it.
What to check before you leave it running
- The firewall rule is scoped to the private profile, not to all profiles
- No port is forwarded on the router unless you have deliberately decided to accept that
- The network the second PC is on is classified as Private in Windows
- You know the port and can remove the rule when you are finished
- The phone is on the same network, on a stand, with its screen timeout off
- The desktop radar was tested and working first, so a blank page has one cause instead of three
Common questions about web radars
Do I need a fuser if I use a web radar?
No. A web radar and a fuser are two different answers to the same need. The web radar gives you a map on another screen, while a fuser gives you an overlay on your main screen.
Can I use the phone over mobile data?
Not without exposing the server to the internet, which means port forwarding and every consequence that comes with it. On the same Wi-Fi, it needs nothing but a firewall rule.
Which port should I use?
Use whatever port your software uses; published projects commonly default to port 80. If something else on the machine already holds that port, change the software's port instead of competing for it.
Is it safe to share the link with a friend?
On your own LAN, it comes down to who is in your house. Over the internet, it means opening a port to an unauthenticated server that reads your game memory, which is not a step to take casually.
Does running a web server on the second PC affect the game PC?
No. It runs on the second PC and talks to browsers over your network. The game PC is not involved, and there is nothing extra there for it to see.
Sources
The published radar projects we refer to are not in our checked source list, and the firewall rule and the phone steps come from bench work.
Read next
- Second monitor, fuser or capture card: how to see the overlay
- Using a capture card instead of a fuser
- How to set up a second PC for DMA
- DMA troubleshooting: fixes for common issues
- What are DMA cheats and how do they work
- The exact cable order for a fuser
- Dichen or GODLIKE: which fuser to buy
- EDID: why a fuser has to look like a monitor
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