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How Two-Factor Authentication Works

Calendr asks for an authenticator code when you sign in. This article covers first-time setup, backup codes, and what to do if you lose your phone.

14 Aug 2026 · by Peter Grillet

Calendr requires two-factor authentication for every user. After you enter your password, or finish signing in with Google or Microsoft, you confirm a code from an authenticator app.

Public booking pages are unchanged. Only signing in to Calendr itself uses two-factor authentication.

What you need

An authenticator app stores a secret for Calendr and shows a new 6-digit code every 30 seconds.

You can use:
Any app that supports standard authenticator codes (TOTP) will work.

First-time setup

The first time you sign in after this is turned on, Calendr shows a setup screen instead of the dashboard.
  1. Sign in as usual.
  2. Open your authenticator app.
  3. Scan the QR code on the setup screen.
  4. If you cannot scan, enter the key shown under the QR code.
  5. Type the 6-digit code from the app into Calendr.
  6. Choose Confirm and continue.
  7. Save the backup codes on the next screen. Calendr shows them once.
After that, you reach the dashboard as normal.
If you are already signed in when this is rolled out, the setup screen appears on your next request. You can sign out from that screen if you need to finish later.

Signing in after setup

  1. Enter your email and password, or continue with Google or Microsoft.
  2. Enter the current 6-digit code from your authenticator app.
  3. Choose Verify.
You can also enter an unused backup code instead of the 6-digit code.

Backup codes

Backup codes are one-time codes. Use one if you cannot open your authenticator app.

Store them somewhere private, not in the same place as your Calendr password. Each code works once. When you are running low, replace your authenticator from Profile Settings to generate a new set.

Replace your authenticator

Use this if you get a new phone, or you want a new set of backup codes.
  1. Sign in and complete two-factor authentication.
  2. Open Profile Settings.
  3. Under Two-factor authentication, enter a current authenticator code or a backup code.
  4. Choose Replace authenticator.
  5. Scan the new QR code and confirm.
  6. Save the new backup codes.
Your old authenticator stays valid until you confirm the new one.

If you lose your phone

  1. Sign in with your password or Google/Microsoft.
  2. On the code screen, enter an unused backup code.
If you do not have a backup code, contact Calendr support. We can reset two-factor authentication on your account. You will set it up again the next time you sign in.
#security #sign-in #two-factor

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