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OpenFrequency

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

v3.9-beta-ef 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.
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Download OpenFrequency-v3.9-beta-ef-Setup.msi
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Version v3.9-beta-ef 2026-04-30
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 Datalink — Controller-Pilot data link with pre-departure clearance, oceanic, and en-route messaging support
NEWMetric RVSM — Auto-switch to metric altitude levels when operating in Chinese airspace
NEWMSI Installer — WiX 4 MSI with major-upgrade support, Start Menu and Desktop shortcuts
NEWDual LLM Models — Configure lightweight and reasoning models; complex situations auto-escalate to the reasoning model
NEWLocal Streaming TTS — Switch between Edge-TTS and a local streaming TTS model; models stored in AppData
IMPROVEDATC Proactive Speaking — Better local-rule detection before invoking AI — fewer false positives, more timely interventions
IMPROVEDRadio Effects — Improved band-pass noise filter; cabin audio now plays without radio effect
FIXEDLAN Dashboard Access — Dashboard was unreachable from other devices on the local network
FIXEDCareer Callsign Lock — Callsign 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 Calculation — Vertical 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.
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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