Device manufacturers may submit payload formatters designed to work with their devices. The source code for these is publicly available in the lorawan-devices Github Repository and the devices are on display in The Things Industries Device Repository.
If you’re a device manufacturer and you’d like to add your device to the open source device repo, find out how here. Adding your device makes it easy for users to use it with The Things Stack, and is a good way to publicly document information and code related to your device.