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OpenFrequency

The AI ATC for Everyone — free, open-source, and powered by LLMs. No subscription. No compromise.

v3.9-beta MIT MSFS · X-Plane 12 Free Forever
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Windows Installer
MSI installer for Windows 10/11 (x64). Creates Start Menu and Desktop shortcuts. Models and config stored in %APPDATA%\OpenFrequency.
Download OpenFrequency-v3.9-beta-Setup.msi
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Version v3.9-beta 2026-04-29
SHA-256 Verified automatically on install
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LLM-Powered ATC
Context-aware ATC powered by Gemini, OpenAI, or Gemma. Remembers your flight plan, handles complex clearances, and speaks naturally.
GeminiOpenAIGemma
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CPDLC Datalink
Controller–Pilot Data Link Communications for pre-departure clearance, oceanic, and en-route messages. Dual LLM routing for quality.
PDCOceanicEn-route
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Bilingual ATIS
Chinese airports automatically generate full English + Chinese ATIS with proper CAAC-style phrasing and metric RVSM levels.
CAACMetric RVSM
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Smart Taxi Routing
Graph-based weighted path planning. Knows real taxiway names, avoids hotspots, and highlights your route on the live map.
OSMX-Plane apt.dat
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Career Mode
Build your pilot career from student to captain. Airline contracts, SimBrief integration, XP system, and violation tracking.
SimBriefXPLicenses
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Voice & TTS
Edge-TTS cloud voices or local streaming TTS. Radio noise filter, radio-free cabin audio, and aviation pronunciation rules.
Edge-TTSKokoroPTT
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Radar Vectoring
Issue HDG / ALT / SPD vectors from the dashboard. Live flight map with altitude coloring, traffic markers, and route prediction.
HDGALTSPD
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Plugin System
Community plugin support with lifecycle hooks. Built-in DLC catalog browser — one-click FlyByWire A32NX download to MSFS.
DLCA32NX
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Auto-Update
Daily update checks via Cloudflare Workers with SHA-256 verification. China-accelerated downloads. Crash telemetry (opt-in).
CloudflareSHA-256
NEWCPDLC DatalinkController-Pilot data link with pre-departure clearance, oceanic, and en-route messaging support
NEWMetric RVSMAuto-switch to metric altitude levels when operating in Chinese airspace
NEWMSI InstallerWiX 4 MSI with major-upgrade support, Start Menu and Desktop shortcuts
NEWDual LLM ModelsConfigure lightweight and reasoning models; complex situations auto-escalate to the reasoning model
NEWLocal Streaming TTSSwitch between Edge-TTS and a local streaming TTS model; models stored in AppData
IMPROVEDATC Proactive SpeakingBetter local-rule detection before invoking AI — fewer false positives, more timely interventions
IMPROVEDRadio EffectsImproved band-pass noise filter; cabin audio now plays without radio effect
FIXEDLAN Dashboard AccessDashboard was unreachable from other devices on the local network
FIXEDCareer Callsign LockCallsign was incorrectly locked to mission callsign after switching to free flight
FIXEDATIS Always "Alpha"Information letter was stuck at Alpha instead of advancing each update cycle
FIXEDV/S CalculationVertical speed was not computing correctly in certain simulator states
1
Install
Run the MSI installer. OpenFrequency creates its config in AppData on first launch.
2
Configure
Add your Gemini API key (free tier) and select your simulator in the Settings page.
3
Fly
Load a SimBrief plan, spawn your aircraft, and press Push-to-Talk to speak to ATC.
4
Immerse
Real cabin crew, bilingual ATIS, radar vectoring, taxi guidance — full flight experience.
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Microsoft Flight Simulator
2020 · 2024 · SimConnect (auto-bundled)
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X-Plane 12
Local Web API · LiveTraffic support
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Prepar3D · FSX
SimConnect compatible
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Operating System
Windows 10 / 11 (x64)
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Simulator
MSFS 2020/2024 · X-Plane 12
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API Key
Google Gemini (free tier)
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Price
Free & Open Source