Ente Auth, 2FAS, and Proton Authenticator are the strongest fits if you need one open-source authenticator available on both Android and iPhone. Choose among them based on how you want to sync and recover your codes. Android users who prefer a local vault and manual backups should also consider Aegis; it does not meet the iPhone requirement.
Best open-source authenticator apps at a glance
| App | Platforms | Backup and sync | Open-source scope | Best fit |
|---|---|---|---|---|
| Ente Auth | iOS, Android, desktop, and web, according to Ente’s comparison. | Ente describes end-to-end encrypted sync and import/export. It says the app can be used locally without an account; an account enables sync. | Ente says both its client and server are open source. | People who want cross-platform access and optional account-based sync. |
| 2FAS | iOS, Android, and a browser extension, according to Ente’s comparison. | The comparison lists Google Drive or iCloud backup and import/export. Confirm the current backup and restore steps for your platform before relying on them. | Ente’s comparison identifies both the client and server as open source. | People who want a mobile authenticator with a browser extension. |
| Proton Authenticator | iOS and Android; Proton links to mobile downloads from its support page. | Proton says you can start without an account, import codes from several named apps, and export codes. A Proton account enables end-to-end encrypted sync; Proton describes encrypted backups when using an account or on iOS. | Proton says all its apps, including Proton Authenticator, are fully open source. Ente’s comparison describes the client as open source and the server as proprietary, so the scope depends on the source being consulted. | People who want optional account-based sync and documented import and export. |
| Aegis | Android only, according to the project documentation. | Supports manual import and export, plaintext or encrypted export, and automatic vault backups to a location you choose. | The project presents Aegis as open source and local; its Google Play listing identifies it as GPLv3. | Android users who want local vault control and are comfortable managing backups. |
The comparison information for Ente, 2FAS, and some Proton details comes from Ente, a vendor comparing its own product with competitors. Treat its competitor claims as a starting point, not an independent audit. Proton’s support page and Aegis’s project documentation provide primary information for those products.
Which authenticator works on both Android and iPhone?
Ente Auth, 2FAS, and Proton Authenticator are listed for both iOS and Android in the available product information. Aegis is an Android-only option, so it is not suitable if you need to use the same authenticator on an iPhone.
Platform availability is only the first check. Before choosing, consider whether you want codes to sync between devices, whether you are comfortable with an account-based service, and how you will recover the codes if your phone is lost or replaced.
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- POWERFUL SECURITY KEY: The Security Key C NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key C NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key C NFC via USB-C and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
How to choose based on backup and recovery
Choose Ente Auth for optional encrypted sync
Ente describes end-to-end encrypted sync, along with import and export. It says you can use the app without an account, while an account enables syncing. This makes it a candidate if you want cross-platform coverage but also want the option to use the app locally. Verify the current account and recovery behavior in Ente’s feature comparison before depending on a particular setup.
Choose 2FAS if the browser extension matters
Ente’s comparison lists a 2FAS browser extension and Google Drive or iCloud backup, as well as import and export. The comparison does not establish the details needed to assess backup encryption or a restore workflow. Check 2FAS’s current instructions for your device and backup provider before storing your only recovery copy there.
Rank #2
- POWERFUL SECURITY KEY: The YubiKey 5C NFC is the most versatile physical passkey, protecting your digital life from phishing attacks. It ensures only you can access your accounts
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5C NFC secures 100+ of your favorite accounts, including email, password managers, and more
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5C NFC via USB and tap it, or tap it against your phone (NFC), to authenticate. No batteries, no internet connection, and no extra fees required
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it
- PRIMARY & SPARE KEYS: Just like having a spare house key, we recommend buying two YubiKeys - one for daily use and one as a spare. That way you’ll never get locked out of your accounts
Choose Proton Authenticator for documented imports and optional account sync
Proton says you can begin without an account and import from Google Authenticator, 2FAS, Aegis, Bitwarden Authenticator, Ente Auth, and LastPass Authenticator. It also supports exporting codes. A Proton account enables end-to-end encrypted sync; Proton describes encrypted backups when using an account or on iOS. Read Proton’s support information for the conditions that apply to your setup.
Choose Aegis for a local Android vault
Aegis focuses on a local vault, with manual import and export and automatic backups to a location you choose. Exports can be plaintext or encrypted. An encrypted export better protects a backup file if it is exposed, but it also means you must retain whatever is needed to decrypt it. Aegis’s project documentation explains its available options.
Rank #3
- POWERFUL SECURITY KEY: The YubiKey 5 NFC is the most versatile physical passkey, protecting your digital life from phishing attacks. It ensures only you can access your accounts
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5 NFC secures 100+ of your favorite accounts, including email, password managers, and more
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5 NFC via USB and tap it, or tap it against your phone (NFC), to authenticate. No batteries, no internet connection, and no extra fees required
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it
- PRIMARY & SPARE KEYS: Just like having a spare house key, we recommend buying two YubiKeys - one for daily use and one as a spare. That way you’ll never get locked out of your accounts
What “open source” means for an authenticator
Open-source status can apply to the mobile app, the server that handles sync, or both. A source-available client does not by itself establish that the service’s backend is open source. In this comparison, Ente says both its client and server are open source; Ente’s comparison describes Proton Authenticator’s client as open source and server as proprietary, while Proton says all its apps are fully open source. Those statements use different scopes, so check what each vendor means rather than treating the label as a simple yes-or-no security score.
Open source also does not prove that a particular app build or server deployment has been independently audited. It is one factor to weigh alongside device security, backup protection, recovery options, and whether you trust the service or prefer to manage data locally.
Rank #4
- POWERFUL SECURITY KEY: The Security Key NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key NFC via USB-A and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
How to transfer authenticator codes to a new phone
- Check the current app’s transfer options. Confirm that it supports export or a documented transfer method and that the destination app can import that format. Proton documents imports from several popular authenticators, including Aegis, 2FAS, and Ente Auth. Aegis also documents importing from several authenticator apps.
- Set up the new phone before removing the old app. Install the destination authenticator and use its import or transfer instructions. For app-specific steps, consult Proton’s support page or Aegis’s project documentation.
- Verify the codes while you still have access to the old phone. Test sign-ins to the services that matter most, using each service’s normal login flow. Do not assume a successful import means every account transferred correctly.
- Make a separate recovery plan. Create and securely store a backup using the destination app’s supported method. For Aegis, that may be an encrypted export or automatic vault backup; Proton documents export and encrypted backup cases. Follow the app’s current instructions and protect any export file and its decryption information.
- Retire the old copy only after verification. Keep the old app available until you have tested the new setup and confirmed you can access your accounts. Then remove old copies and temporary export files you no longer need, taking care not to destroy your only recovery option.
Can you back up 2FA codes without putting them in the cloud?
Yes. Aegis supports local vault backups to a location you choose and manual exports, including encrypted exports. Ente says it can be used without an account, though an account enables its sync feature. Local-only use avoids account-based syncing, but it makes you responsible for keeping a secure backup somewhere you can access if the phone is lost or damaged. A backup kept only on the same phone is not a reliable recovery plan.
Quick Recap
Best Value
- POWERFUL SECURITY KEY: The YubiKey 5 is a versatile physical passkey that protects your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5 secures 100+ of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5 via USB and tap it to authenticate. No batteries, no internet connection, and no extra fees required.
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
Security checks before switching
- Confirm platform support: Aegis is Android-only; the other three options in the comparison are listed for both iOS and Android.
- Understand where backups go: Ente and Proton describe end-to-end encrypted sync options; Ente’s comparison lists Google Drive or iCloud backups for 2FAS. Check the app’s own current documentation for the exact storage and restore behavior.
- Keep recovery material protected: Treat exported code files and backup credentials as sensitive. Do not leave plaintext exports in a shared or unprotected location.
- Test before deleting: Verify account access on the new phone and confirm that your recovery method works before retiring the prior app.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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