The Firebase Admin SDK provides us an ability to authenticate the user with an external mechanism such as LDAP server, or third-party OAuth provider, which Firebase doesn't support, such as Instagram or LinkedIn. We can do all these things with Firebase custom tokens method, which is built-in Admin SDK, or we can use any third-party JWT libraries.
Let's see how we can create and validate token with Admin SDK.
For creating a custom token, we must have a valid uid, which we need to pass in the createCustomToken() method:
function createCustomToken(req,res){ const userId = req.body.uid "guest_user" admin.auth().createCustomToken(userId) .then(function(customToken) { res.send(customToken.toJSON()); }) .catch(function(error) ...