Getting started

KlarFunk does not run in a browser tab. The platform serves the download; the app runs locally on your Mac or PC. Five minutes from here to your first coordinated frequency.

1. Download and install

Download KlarFunk free from the download section of the product page — no account, no licence needed. Every install runs a 14-day full-feature trial. To keep using it afterwards, buy a key once on Gumroad (€49) and enter it in the app — see Licence, trial and your data.

Pick the file for your machine:

Not sure which Mac you have? Apple menu → About This Mac. "Apple M…" means Apple Silicon; "Intel Core" means Intel.

macOS: open the .dmg, drag KlarFunk onto the Applications folder, eject the disk image.

Windows: run the installer, then start KlarFunk from the Start Menu.

No Python, no Homebrew, nothing to compile. On macOS there's nothing to install — the RTL-SDR library ships inside the app. On Windows, run 'KlarFunk - Install RTL-SDR Driver' once from the Start menu (the installer puts it there), then plug in and go. Step 3 below walks you through it. You do not open a terminal to use it.

2. First launch

KlarFunk is not signed with an Apple Developer ID or a Windows code-signing certificate yet, so both systems warn you once.

macOS refuses to open the app the first time. Either of these clears it, once:

• Open System Settings → Privacy & Security, scroll down to Security, click Open Anyway, confirm. Then open KlarFunk again.

• Or paste this into Terminal, press Return, and open the app normally:

  xattr -dr com.apple.quarantine "/Applications/KlarFunk.app"
  

Windows shows a SmartScreen warning when you run the installer. Click More info → Run anyway. If you want to check the download first, every installer's SHA-256 hash is published next to it on the release page.

The first launch takes a little longer than the rest. On an older Intel Mac it can be 30–40 seconds. A splash screen shows while the scanner engine starts.

3. Plug in your device

Connect your RTL-SDR, tinySA or RF Explorer before you start the app (HackRF and Airspy: Apple Silicon macOS only — hardware-unverified, see Supported hardware). KlarFunk detects it automatically; there is nothing to select.

If you plug it in later, click Re-check device in the amber banner at the top. The app tries again without restarting.

4. Your first scan

Click Start scan or press Space. The default sweep covers 470–700 MHz, the wireless-mic band, and a full pass takes a few seconds. Leave it running; each sweep redraws the spectrum.

No device connected? You still get a spectrum. KlarFunk drops into demo mode with a synthetic signal that includes plausible TV transmitters, mic carriers and the LTE edge. The amber banner "Demo mode — synthetic spectrum, no supported device detected" tells you it is not real. No banner means real hardware.

5. Reading the spectrum

• The bright trace is the current sweep; the faint one behind it is the previous sweep.
• The dashed horizontal line is the noise threshold. Anything above it counts as occupied.
• Coloured fills mark what is above the threshold. Once you have registered your own equipment they mean three different things: green is one of your own carriers, amber is something else sitting on a channel you use, red is an unknown signal.
• The Free channels and Occupied ranges cards under the spectrum list the same information as numbers, sorted, ready to read out over a headset.

Type a frequency in MHz into the lookup field to get a free / occupied verdict for that exact spot.

6. Change the language

The interface is available in English, German, French, Spanish, Italian, Dutch and Portuguese. Pick one from the language menu in Settings. The choice is remembered for next launch.

Next

• Turn a scan into usable windows: Find a free frequency window.
• Register the gear you actually carry: Register your equipment.
• Let the Advisor build the whole plan: Coordinate a show with the Frequency Advisor.