The download contains the server and the HTML that will be displayed in OBS
The server is compiled for Windows currently but is written in the Go programming language and can easily be compiled for other operating systems if needed
Unzip the download
Run the local server by double-clicking heart-of-frogg.exe
Input your computer's internal IP address (as shown by heart-of-frogg.exe on server start) and the heart-of-frogg.exe server's port ("8080" by default) into the "Heart of Frogg" Fitbit app settings on your phone
Start the "Heart of Frogg" watch app on your Fitbit device
Create a web source in OBS that points to http://localhost:8080/ui/index.html
Play a game that gets your heart rate pumping!
Customization
Server Port
The heart-of-frogg.exe server defaults to using port 8080. If you already use port 8080 for something else, you'll need to change the server port. To do this, edit config.toml to contain the port number you want to use. You'll need to restart the server and then update your Fitbit settings and OBS web source to use the new port number.
UI
/ui/index.html is what's shown in OBS. If you want to customize what it looks like, go ahead! Tweak to your liking and then refresh your OBS source to see your changes. See the "How It Works" section below for details.
How It Works
The heart-of-frogg.exe server listens for HTTP POST calls at http://localhost:8080/heart/:rate
The Fitbit app checks your heart rate and then makes an HTTP POST call with the heart rate value to the server (e.g. http://192.168.1.101:8080/heart/86)
OBS loads /ui/index.html as a source which uses JavaScript to periodically do an HTTP GET request to http://localhost:8080/heart to retrieve your current heart rate as reported to the server by your watch