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Sign-in methods 🔐

Welcome screen — entry point to sign in or sign up

RedKiwi supports the following sign-in methods. Which buttons you see depends on your device and language settings.

MethodWhen it shows
📧 Email + passwordEveryone
🔵 GoogleEveryone
🟦 FacebookEveryone
⚫ AppleiOS devices only
🟡 KakaoWhen the app language is Korean
💚 LINEWhen the app language is Japanese
Sign-in screen — supported login methods

⚠️ Important: sign in with the same method you used to sign up

Section titled “⚠️ Important: sign in with the same method you used to sign up”

Trying a different sign-in method than the one you signed up with creates a totally separate account.

Examples:

  • Signed up with Google → tried Kakao → created a new, different account
  • Your existing study record stays in the original Google account

If you can’t remember which method you used:

  1. Try the SNS you use most (Google or Kakao are most common)
  2. If not, try Apple (iPhone users) or LINE
  3. If nothing works, contact support

You can link several sign-in methods to one account. Once you do, signing in with any of them takes you to the same account.

  1. Settings → Account info → “SNS account linking”
  2. Pick the SNS you want to link
  3. Complete the SNS sign-in
  4. Done!

Same screen — tap “Unlink.” Note: your last remaining sign-in method can’t be unlinked (otherwise you’d have no way to sign in).

When you link Kakao, your marketing consent is automatically reflected in your profile.


You can see all currently linked sign-in methods in Settings → Account info.

The ones marked “Connected” are currently active sign-in methods.


  • At least 6 characters
  • No spaces

”The email address you have entered is not registered.”

Section titled “”The email address you have entered is not registered.””
  • No account exists with this email
  • Maybe you signed up via SNS — try that instead
  • You’ll need to reset your password
  • On the sign-in screen, tap “Forgot password” to get a reset link

”You’ve exceeded the password reset attempt limit.”

Section titled “”You’ve exceeded the password reset attempt limit.””
  • Wait a while and try again (security limit)

“This email is already in use.” (during signup)

Section titled ““This email is already in use.” (during signup)”
  • An account with this email already exists
  • Try signing in on the sign-in screen
  • You’ll need to contact support
  • For sensitive actions (changing email, deleting account), recent sign-in is required
  • Sign out and back in → retry

Settings → Logout button → “Do you really want to logout?” confirmation → signed out.

Signing out doesn’t delete your account. Sign back in with the same method and your study record returns intact.