> For AI agents: the complete documentation index is available at https://docs.flashnerd.com/llms.txt, the full documentation bundle is available at https://docs.flashnerd.com/llms-full.txt.

# Sign in and link accounts

Flashnerd requires sign-in before you can use the app. Google sign-in is available on iPhone and Android; Apple sign-in is available on iPhone.

## Sign in

1. Connect your phone to the internet and open Flashnerd.
2. Choose **Sign in with Google**, or **Sign in with Apple** on iPhone.
3. Complete the provider's sign-in flow using the account you want associated with Flashnerd.
4. Wait for Flashnerd to open your collection.

On the same installation, returning to the same Flashnerd account reopens that account's local profile. Choosing a different, unlinked provider account can open a different Flashnerd account with a different local collection.

:::info
Signing in identifies your account. It does not download decks from another device. Use an [exported collection backup](https://docs.flashnerd.com/guide/import-export/backups.md) to move study data.
:::

## Check your account

Open **Settings**, then tap the account card to open **Account Info**. Check **Account ID**, **Account Status**, and **Linked Accounts** when you need to confirm which account is active.

If your collection appears empty after sign-in, first check that you used the expected provider account. Avoid deleting the account or clearing app storage while investigating missing data.

## Link another sign-in method

Linking lets another provider access the same Flashnerd account. It does not merge two already separate Flashnerd collections.

1. Sign in to the Flashnerd account you want to keep using.
2. Open **Settings → Account Info → Linked Accounts**.
3. Tap **Link** next to the available provider.
4. Complete that provider's authentication flow.
5. Check that the row now says **Linked**.

Apple linking is available on iPhone. Before relying on Google to access an Apple-linked account from Android, link the intended Google account on your iPhone first.

If a provider account is **Already in Use**, it belongs to another Flashnerd account. Choose another provider account or sign in to the existing account; linking is not an account-merging action. **Already Linked** can mean that this Flashnerd account already has a different sign-in attached for that provider.

## Unlink a method

1. Confirm that another linked method is available and that you can use it.
2. In **Linked Accounts**, tap **Unlink** beside the method to remove.
3. Read and confirm the dialog.

You must keep at least one linked method. Removing one means it can no longer sign you in to that Flashnerd account. If the app asks for a recent sign-in, [log out and sign back in](https://docs.flashnerd.com/guide/accounts/sign-out-and-delete.md) with a linked method, then retry.

For connection and session problems, see [local data and offline use](https://docs.flashnerd.com/guide/accounts/offline-and-data.md) and [troubleshooting](https://docs.flashnerd.com/help/troubleshooting.md#sign-in-and-missing-data).