They all generate the same codes
Let’s get this out of the way: every authenticator app that supports TOTP produces the same 6-digit codes. The algorithm is standardized (here’s how TOTP works if you’re curious). So the codes from Google Authenticator, Authy, and a random open-source app are identical for the same secret key.
The differences come down to everything around the codes: backup options, multi-device support, the interface, and whether you trust the company behind the app.
Here’s how five popular options stack up.
The comparison
| Feature | Google Authenticator | Microsoft Authenticator | Authy | 2FAS | Aegis |
|---|---|---|---|---|---|
| Platform | Android, iOS | Android, iOS | Android, iOS, Desktop | Android, iOS | Android only |
| Cloud backup | Google account sync | iCloud / Google backup | Encrypted cloud sync | Google Drive / iCloud | Manual export only |
| Multi-device | Via Google sync | One phone + backup | Yes, built-in | Via cloud backup | No |
| Open source | No | No | No | Yes | Yes |
| Offline use | Yes | Yes | Yes | Yes | Yes |
| Biometric lock | No | Yes | Yes | Yes | Yes |
| Price | Free | Free | Free | Free | Free |
Google Authenticator
Google Authenticator is the app most people think of when they hear “authenticator.” It’s been around since 2010, and for most of its life it was deliberately bare-bones: no backup, no sync, no frills. You had your codes on one device, and if you lost that device, you were starting over.
That changed in 2023 when Google added account sync. Your secrets now back up to your Google account and restore when you sign in on a new device. This fixed the biggest complaint about the app.
It’s still minimal. There’s no PIN or biometric lock on the app itself, which means anyone who picks up your unlocked phone can see your codes. The interface is clean but basic. It works fine.
Good for: People who want something simple from a name they recognize. If you already live in Google’s ecosystem, the sync is convenient.
Watch out for: No app-level lock. Your codes are only as protected as your phone’s lock screen.
Microsoft Authenticator
Microsoft’s app does more than TOTP. It handles push-notification approvals for Microsoft accounts, can store passwords, and supports autofill. If you use Microsoft 365 at work, there’s a decent chance your IT department has already pointed you toward this one.
For TOTP specifically, it works well. It supports iCloud backup on iOS and Google account backup on Android. The app has a biometric lock option, so you can require Face ID or a fingerprint before codes are visible.
The interface is busier than Google Authenticator because of all the extra features. If you’re only using it for TOTP codes, there’s a lot of stuff you’ll ignore.
Good for: People already in the Microsoft ecosystem, especially if you use it for work. The push notifications for Microsoft 365 login are genuinely convenient.
Watch out for: The app can feel cluttered if you don’t use the password manager or autofill features.
Authy
Authy was one of the first authenticators to offer encrypted cloud backup and multi-device sync, back when Google Authenticator still had neither. You can install Authy on your phone, tablet, and desktop, and all your codes stay in sync.
The backups are encrypted with a password you set (separate from your Authy account password). Authy can’t read your secrets on their servers, at least according to their documentation.
One thing to know: Authy discontinued their desktop apps in 2024. If desktop access was a selling point for you, that’s gone now. The mobile apps still work and still sync.
Authy is owned by Twilio, a large communications company. It’s not open source, so you’re trusting Twilio’s implementation and infrastructure.
Good for: People who want automatic multi-device sync without thinking about it. The setup is straightforward and the backup is built in.
Watch out for: Not open source. Desktop apps are discontinued. You’re trusting Twilio with your encrypted vault.
2FAS
2FAS is the open-source option that doesn’t make you give up convenience. It supports cloud backup through Google Drive or iCloud, has a clean interface, and includes a browser extension that can auto-fill TOTP codes when you log into websites.
Being open source means the code is publicly auditable. If you care about verifying what an app is doing with your secrets, this matters.
The browser extension is a nice touch. When a site asks for your TOTP code, you get a notification on your phone to approve it, and the code fills automatically. It’s similar to how push-notification 2FA works, but built on standard TOTP.
Good for: People who want open-source software without sacrificing usability. The browser extension is a real convenience feature.
Watch out for: Smaller community than the big names. Less name recognition if that matters to you for trust.
Aegis
Aegis is Android-only and fully open source. It’s the most transparent option here: no cloud service, no account to create, no sync unless you set it up yourself. You export an encrypted vault file and manage backups however you want.
The app supports biometric lock, has a clean interface, and handles all the standard TOTP/HOTP stuff without fuss. You can import from most other authenticator apps if you’re switching.
The lack of built-in cloud sync is either a feature or a drawback depending on your perspective. If you want full control over where your secrets are stored, Aegis gives you that. If you want things to just sync automatically, you’ll need to pair it with something like Syncthing or manage manual backups.
Good for: Android users who want full control and transparency. Security-minded people who prefer to manage their own backups.
Watch out for: No iOS version. No built-in sync. You’re responsible for your own backup strategy.
So which one should you use?
There’s no single best answer. Here’s a rough decision guide:
- You just want something that works: Google Authenticator or Microsoft Authenticator. Pick whichever ecosystem you already use.
- You want cloud sync across multiple devices: Authy or 2FAS.
- You care about open source: 2FAS (cross-platform) or Aegis (Android).
- You want maximum control: Aegis. You manage everything, nothing phones home.
- You use Microsoft 365 at work: Microsoft Authenticator, since you probably need it anyway.
The honest truth is that any of these apps is fine. The security difference between them is small compared to the difference between using any authenticator app and not using one at all. Pick one, set up your accounts, save your backup codes, and move on.
If you want to understand the mechanics behind the codes these apps generate, check out What is TOTP?. And to test codes without committing to anything, try 2fa.zip — it runs in your browser and doesn’t store anything on a server.