# Environment Variables There are a number of environment variables we use at build time to influence the output application's behavior. ```bash # Application NODE_ENV=< production | development > DEBUG=< true | false > APP_CONFIG=< relative path to application configuration file > PUBLIC_URL=<> VERSION_NUMBER= BUILD_NUM= # i18n USE_LOCIZE= LOCIZE_PROJECTID= LOCIZE_API_KEY= ``` ## Setting Environment Variables - `npx cross-env` - `.env` files - env variables on build machine, or for terminal session