Plain Flags back end is best installed and run as Docker containers. Below are two examples.

To use the Plain Flags SDK, install it as follows:
NodeJs (TypeScript)
npm install plain-flags-node-sdk
Go (Golang)
go get github.com/andreileonte1981/plain-flags/sdk/go

Plain Flags source code is freely available.

You can choose to build and run your own installation from the source code: github repository