Keep your transceiver and a public WebSDR perfectly in step. Tune the rig — the WebSDR follows. Click the WebSDR waterfall — the rig retunes. Frequency and mode, both ways.
⊞ Windows 10 / 11 only
Cat2Web recognises the receiver type on its own — open any of these and it just works.
The original multi-user WebSDR servers (like the University of Twente). Full frequency, mode and audio control.
The worldwide KiwiSDR network — hundreds of public receivers, tuned straight from your rig.
The open-source web SDR, including the popular OpenWebRX+ fork.
Native protocol with no browser at all — Airspy R2 / Mini / HF+ direct, for the lowest latency.
If you can’t always hear the band from home, Cat2Web lets a remote receiver do the listening while you stay on your own rig.
City QTH drowning in noise? Let a quiet remote WebSDR do the receiving while you transmit on your own radio.
Track your TX VFO to hear exactly where a DX station is listening, then drop right in.
Follow a net on a clear remote receiver even when your own antenna can’t quite pull it in.
Check your own signal and audio from the other side of the world, in real time.
Cat2Web is a Windows app that links a real transceiver with public SDR receivers — the browser-based ones (classic WebSDR, KiwiSDR, OpenWebRX / OpenWebRX+) and, uniquely, native SpyServer (Airspy) receivers with no browser at all. Listen to how you sound on the air from the other side of the world, or spot on your own frequency — all kept in sync automatically.
Rig → WebSDR, WebSDR → Rig, or fully bidirectional. Frequency and mode (CW / USB / LSB / AM / FM …) stay matched, with echo suppression so the two never fight.
Follow your receive or your transmit frequency — so you can hear your own signal on a remote WebSDR even when working split.
The WebSDR audio is muted while you transmit — no feedback howl — then comes back the moment you stop.
An embedded Chromium browser (WebView2) opens the receiver page and recognises the SDR type on its own — no per-site setup.
Works with any rig OmniRig supports — the CAT standard thousands of hams already use — polled smoothly in the background.
Run it from a USB stick with its own settings, or install normally. No account, no cloud — everything stays on your PC.
Everything a classic CAT-to-WebSDR tool does — plus three things they don't.
Beyond the browser SDRs, C2W talks the native SpyServer (Airspy) protocol directly — Airspy R2 / Mini / HF+. It pulls the IQ stream, demodulates and plays the audio itself, with no browser involved: lower latency and rock-solid sync. No other CatSync-style tool does this.
Control a FlexRadio 6xxx / 8xxx directly over your LAN through the SmartSDR TCP API. C2W discovers the radio automatically (UDP broadcast) — no serial cable, no virtual COM ports, no OmniRig needed for Flex.
And with Flex it syncs the filter bandwidth too — not just frequency and mode. Narrow down on the rig and the receiver follows the exact passband width.
Expert Electronics rigs — SunSDR2 / DX / PRO and MB1 — speak the TCI protocol over the network. C2W drives their frequency and mode straight through TCI, no CAT cable and no COM port. This backend is brand-new and marked beta: SunSDR owners are warmly invited to try it and send feedback.
Send the WebSDR receive audio to any sound device on your PC — headphones or a second interface. Not just the default output.
The demo is fully functional for a limited trial period. Unlock the full app for good with a single license.
After payment you enter your callsign; your personal license key is emailed to you (usually within a few hours). The key carries your callsign and your name, and the app shows both. Prices include any applicable VAT.
No account, no server check — activation is a single key you paste into the app.
Grab the free demo for Windows 10/11 — fully functional for a limited time — and try it with your rig and any WebSDR.
Pay €20 once and enter your callsign at checkout.
Your personal license key arrives by email, keyed to your callsign and name.
Click “Enter code” in the app, paste the key, press Activate. Done — offline, forever.
Fully functional for a limited trial period — no features locked.
The download is a single .exe — there is no installer. The very first time you open it, Windows may show two safe, one-time prompts: SmartScreen (the app isn’t code-signed yet) and the Firewall (C2W needs the local network for FlexRadio and SpyServer). Just allow both — they won’t appear again.
Yes — the demo is fully functional for a limited time, so you can confirm everything works with your setup before you buy.
Yes. Cat2Web does the same core job — keeping your transceiver and a public WebSDR in sync — and adds native SpyServer (Airspy) support, FlexRadio and SunSDR (TCI) network control, filter-bandwidth sync and audio-output routing. If you’ve used a CatSync-style tool you’ll feel right at home; the free demo lets you compare on your own station.
No. It's a single one-time payment of €20 for a lifetime license, including future updates.
Just ask — the key is generated from your name and callsign, so the exact same key can be re-issued to you free, any time. There's no database and no reinstall limit.
Yes. The license isn’t tied to a machine and there’s no activation server — the same key works on any PC. It’s kept as a small license.key file next to the app (or in %APPDATA%), so if you run C2W portably from a USB stick it stays activated wherever you plug it in. On a new PC without that file, just paste your key once.
The browser SDRs — classic WebSDR, KiwiSDR, and OpenWebRX / OpenWebRX+ (auto-detected per page) — plus native SpyServer (Airspy R2 / Mini / HF+) receivers with no browser.
Almost any modern rig. FlexRadio 6xxx / 8xxx are controlled directly over the network; every other transceiver goes through OmniRig, the widely-used CAT engine. If OmniRig can talk to your rig — essentially all current Icom, Yaesu, Kenwood, Elecraft and many more — it works with Cat2Web. OmniRig is configurable too, so less common rigs can be added via its rig-definition files. SunSDR / Expert Electronics rigs also have a dedicated network backend over the TCI protocol (currently in beta).
Yes. C2W controls the rig through OmniRig, which several programs can share at once — so your logger and Cat2Web can both talk to the same radio at the same time. If your station uses a single CAT COM port, a port splitter such as VSPE lets multiple apps share it. FlexRadio’s network control likewise allows several clients at once.
No. Any transceiver supported by OmniRig works over CAT. FlexRadio network control is an extra option for those who have one — no CAT cable required.