> For the complete documentation index, see [llms.txt](https://doc.open-tx.org/manual-for-opentx-2-2/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.open-tx.org/manual-for-opentx-2-2/companion.md).

# Companion

OpenTX comes with a computer-based graphical user interface, OpenTX Companion, that runs on Windows, Mac OS and Linux. It is a great tool to try things even without a radio. It can speed up new model setups because the PC interface is not limited to a small screen and a few buttons. Companion will allow you to:

* Download and install OpenTX transmitter firmware
* Simulate transmitters and models (Try before you buy or fly)
* Edit transmitter and model configurations
* Backup the transmitter’s firmware, models and SD Card contents
* Edit the OpenTX transmitter start up screen (splash screen)