Best Authenticator Apps: Which One to Choose
Five two-factor apps for five different reasons: an auditable open-source option, a lightweight default, multi-device sync, and two that only make sense with a Microsoft or work account.
Five ways to generate the same six-digit code, and the differences that actually matter sit somewhere other than the number itself.
Three apps for anyone, two for one account
Google Authenticator, 2FA Authenticator, and Twilio Authy compete for the same job: a personal second factor for any service that supports TOTP. Pick based on trust model, size, and whether you need more than one device generating codes at once.
Microsoft Authenticator and Duo Mobile are a different category. Both generate the same plain codes, but their actual value is tied to an account or an employer you either have or don't — comparing their "features" against the first three misses the point.
What happens when you lose your phone
Google, 2FAS, and Authy all back up your codes now — Google added it in 2023, closing the one real gap it had against Authy for over a decade. 2FAS is the only one where you can actually verify the backup does what it claims, since the code is public.
Either way: save the recovery codes each service shows you when you turn on 2FA, separately from the phone. An app backup covers the app losing your phone. It does nothing if the account itself locks you out for some other reason.
Size varies by six times for the same job
Google Authenticator 39 MB
2FA Authenticator 83 MB
Microsoft Authenticator 223 MB
The extra weight on Microsoft's app goes to device management and passwordless sign-in, not to the codes — irrelevant baggage unless you actually use those features.
Short answer
Most people — Google Authenticator. Proven, light, and syncing finally works.
Want to verify the backup, not trust it — 2FA Authenticator. Same idea, open source.
Work from more than one device daily — Twilio Authy. The one app here built for that from the start.
Microsoft work account — Microsoft Authenticator. Ignore it otherwise.
Duo showed up on your phone by itself — Duo Mobile. You already have your answer.
Running two of these at once adds nothing: codes transfer, and splitting them between apps is just a way to lose track of which one has what.
Best for: most people — the default that finally fixed its one real flaw
Pros
- Free sync and QR-code transfer to a new phone, standard since 2023
- Lightest app in this list at 39 MB
- Broadest, most consistently high rating in the category
Cons
- Backup lives inside your Google account — one password away from both factors
- No PIN or biometric lock on the app itself
- Nothing beyond a plain list of codes — no folders, no notes
The right default. Thirteen years of losing codes with a lost phone ended in 2023, and there's no real reason to look further unless one of the others solves a problem you actually have.
Best for: anyone who wants to verify the backup claim instead of trusting it
Pros
- Source code is public — anyone can check what happens to your codes
- Encrypted backup, functionally the same promise as Google's, but auditable
- Rated as well as Google's despite a fraction of the audience
Cons
- Updates come slower than from Google or Microsoft
- 83 MB for what is, functionally, a list of six-digit codes
- A far smaller company behind it than the other four names here
The honest alternative to taking a giant's word for it. For an app holding every second factor you own, being able to read the code is an argument, not a slogan.
Best for: anyone who signs in from a computer regularly, not just a phone
Pros
- Codes work on phone, tablet, and desktop at the same time — not one device plus a restore
- Encrypted backup years before most competitors had one
- Free, no ads
Cons
- Account is tied to a phone number — the identifier attackers target in SIM-swap fraud
- The gap it used to fill narrowed sharply once Google added its own sync in 2023
- No open-source option to verify how the backup actually works
Still the better pick if you genuinely work from a desktop day to day. For everyone else, the reason to choose it over Google shrank to almost nothing in 2023.
Best for: anyone signing into a Microsoft work or school account
Pros
- Replaces the password outright for Microsoft 365 and Windows sign-in
- Same standard TOTP codes as everything else here, for non-Microsoft accounts too
- Free, with no limits
Cons
- 223 MB — nearly six times Google Authenticator's size
- All of that weight buys nothing without a Microsoft account
- Passwordless setup targets IT-managed accounts, not casual personal use
Worth installing for exactly one reason: a Microsoft work or school account. Without one, it's the heaviest plain code generator on this list and nothing more.
Best for: people whose employer or school already installed it
Pros
- Push-notification approval is faster than typing a code, and harder to phish
- Handles ordinary TOTP codes for personal accounts too
- Largest audience in the category — mostly deployed, not chosen
Cons
- Its real strength lives in the enterprise admin console, invisible to a private user
- Nothing here that Google or 2FAS doesn't already do for a personal account
- You're rarely using it because you picked it
Not a voluntary choice for most people, and that's fine. As a personal TOTP app it's competent but gives no reason to switch to it on purpose.