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AltRepo/Utils/ALT 2FA

ALT 2FA authenticator

ALT 2FA

A local authenticator app for creating 2FA codes from setup keys, QR images, otpauth links, or encrypted backups. It runs in your browser, keeps the workflow simple, and leaves your secrets under your control.

ALT 2FA Chrome extension
Add account
Browser only

Screenshots from account security pages work here. The image is decoded in this browser.

Some services show this link behind a QR code. You can paste it directly when you have it.

Codes

Local accounts

Setup guide

Online authenticator app for setup keys and QR codes

ALT 2FA works like a lightweight authenticator app in your browser: add the setup key a website gives you, then use the changing code when you sign in. Everything is handled on your device, so the QR image, secret key, and generated code are not uploaded.

How the local flow works
Setup key QR image otpauth link Browser only No upload step Web Crypto TOTP code Encrypted backup Your code 428 913 Changes every 30s

What is 2FA?

2FA, or two-factor authentication, means signing in with your password plus one more proof that it is really you. An authenticator app gives you that second proof as a short code that changes every few seconds, which makes a stolen password much less useful on its own.

1

Turn on 2FA

Open the account security settings for the service and choose an authenticator app or TOTP option.

2

Add the setup key

Scan the QR code with the extension, upload a screenshot, or type the Base32 setup key manually.

3

Save recovery codes

Most services give backup codes after setup. Keep those somewhere separate from your browser profile.

Privacy and security mechanism

QR decoding, setup key parsing, TOTP generation, and backup encryption all happen in the browser. The web app stores accounts in local storage, and encrypted backups are protected with Web Crypto using PBKDF2 and AES-GCM before the JSON file is downloaded. There is no account system, sync service, or server-side recovery.

Authenticator app backup and restore

You can export an encrypted JSON backup from the web app and restore that same ALT 2FA backup later with its password. Import also accepts common authenticator formats such as otpauth links, QR images, Aegis JSON, 2FAS JSON, CSV, and simple account arrays.

Web app and extension vault

This web app is a functional local authenticator that stores accounts in this browser's local storage. The extension adds a master-password vault, which is the stronger choice if you want a dedicated browser extension for long-term storage.

ALT 2FA Chrome extension

ALT 2FA Chrome extension

Use the extension when you want the same local-first flow in your browser toolbar, with a master-password vault, QR scanning, encrypted backup export, and faster access while signing in.

Frequently asked questions

What is 2FA?

2FA means two-factor authentication. It adds a second check after your password, usually a short code from an authenticator app, so a stolen password is not enough to sign in.

Can I use this as an online 2FA authenticator?

Yes. ALT 2FA can generate authenticator codes from setup keys, QR images, otpauth links, and imported backups. The codes are generated in your browser.

Why are my 2FA codes wrong?

Check your system clock, algorithm, digit count, period, and whether the service expects TOTP rather than HOTP.

Can the web app replace the extension?

It can generate and manage local TOTP codes, import QR images, and export encrypted backups. The extension is still better for password-protected long-term storage.