Anonymous

The Anonymous plugin allows users to have an authenticated experience without requiring them to provide an email address, password, OAuth provider, or any other Personally Identifiable Information (PII). Users can later link an authentication method to their account when ready.

Installation

import { betterAuth } from "better-auth"
import { anonymous } from "better-auth/plugins"

export const auth = betterAuth({
    // ... other config options
    plugins: [
        anonymous() 
    ]
})

npx @better-auth/cli migrate

npx @better-auth/cli generate

import { createAuthClient } from "better-auth/client"
import { anonymousClient } from "better-auth/client/plugins"

export const authClient = createAuthClient({
    plugins: [
        anonymousClient()
    ]
})

Usage

Sign In

To sign in a user anonymously, use the signIn.anonymous() method.

const user = await authClient.signIn.anonymous()

Link Account

If a user is already signed in anonymously and tries to signIn or signUp with another method, their anonymous activities can be linked to the new account.

To do that you first need to provide onLinkAccount callback to the plugin.

import { betterAuth } from "better-auth"

export const auth = betterAuth({
    plugins: [
        anonymous({
            onLinkAccount: async ({ anonymousUser, newUser }) => {
               // perform actions like moving the cart items from anonymous user to the new user
            }
        })
    ]

Then when you call signIn or signUp with another method, the onLinkAccount callback will be called. And the anonymousUser will be deleted by default.

const user = await authClient.signIn.email({
    email,
})

Options

• emailDomainName: The domain name to use when generating an email address for anonymous users. Defaults to the domain name of the current site.

import { betterAuth } from "better-auth"

export const auth = betterAuth({
    plugins: [
        anonymous({
            emailDomainName: "example.com"
        })
    ]
})

• onLinkAccount: A callback function that is called when an anonymous user links their account to a new authentication method. The callback receives an object with the anonymousUser and the newUser.

• disableDeleteAnonymousUser: By default, the anonymous user is deleted when the account is linked to a new authentication method. Set this option to true to disable this behavior.

• generateName: A callback function that is called to generate a name for the anonymous user. Useful if you want to have random names for anonymous users, or if name is unique in your database.

Schema

The anonymous plugin requires an additional field in the user table: