Third-Party Notices

Last updated: 25 October 2026

ATC Trainer is built with the components below. Each is used under its own license, which is not changed by the License or the Terms of Service. The full license text of each component is available from its project page.

1. Speech recognition

• whisper.cpp (ggml-org) — MIT License, © The ggml authors.
• Whisper model weights (OpenAI, converted to ggml format by the whisper.cpp project: ggml-small.en and ggml-base.en) — MIT License, © OpenAI.

2. Speech synthesis

• Piper (piper-tts 1.7.0, Open Home Foundation) — GNU General Public License v3.0 or later. Piper runs as a separate program in its own container and the Service talks to it over HTTP; the Service itself is not a derivative of it. The source code of the version we run is available at github.com/OHF-voice/piper1-gpl, and we will provide a copy on request (info@atc-trainer.com). Piper includes eSpeak NG (GPL-3.0-or-later) for text-to-phoneme conversion.
• Voice models from the rhasspy/piper-voices collection:
  • en_US-kathleen-low — trained on the Kathleen dataset, released under CC0 (public domain dedication).
  • en_US-amy-medium, en_US-danny-low, en_GB-alan-medium — trained on voice data published by Mycroft AI (mimic3-voices) and fine-tuned from the Lessac and Ryan datasets. The collection is published under the MIT license.
• Voices that an administrator adds later keep the license of their own source.

3. Maps

• MapLibre GL JS 4.7.1 — BSD 3-Clause License, © MapLibre contributors (bundled in the app).
• OpenFreeMap map tiles and styles, © OpenMapTiles, with map data © OpenStreetMap contributors (Open Database License). The attribution is shown on every map.

4. Aviation data

• X-Plane airport data (apt.dat) — GNU General Public License. The Service never ships this data. If you import an airport layout from it, the file's copyright notice is stored unchanged with that layout and shown wherever it is used.

5. Fonts

• IBM Plex Sans Condensed and IBM Plex Mono — SIL Open Font License 1.1, © IBM Corp. (github.com/IBM/plex).

6. Server and browser libraries

Licenses of the NuGet packages included in the application (direct and transitive). MIT, BSD-2-Clause, Apache-2.0 and PostgreSQL licenses all require that the copyright notice and license text travel with the software; the notices are available in each package at nuget.org.

• QuestPDF is used under the QuestPDF Community License, which is free for organizations with annual gross revenue below USD 1 million. We review this when our revenue changes.