GoDotEnv
A Go port of Ruby's dotenv library
... where multiple projects are run. Dotenv load variables from a .env file into ENV when the environment is bootstrapped. It can be used as a library (for loading in env for your own daemons etc) or as a bin command. There is test coverage and CI for both linuxish and windows environments, but I make no guarantees about the bin version working on windows. Existing envs take precedence of envs that are loaded later.