react-native-unique-id generates a guid and stores it in the async store This is supposed to identify the device / user. It creates a guid if no exists and stores it in the AsyncStorage. If a Guid exists, this will be returned Usage npm install react-native-unique-id --save const uniqueId = require("react-native-unique-id"); uniqueId() .then(id => console.log(id)) .catch(error => console.error(error)); // or callback style uniqueId((error, id) => { if (error) return console.error(error); console.log(id);});