two-factor-authentication-best-practices

Setup

1. Add twoFactor() plugin to server config with issuer
2. Add twoFactorClient() plugin to client config
3. Run npx @better-auth/cli@latest migrate (built-in adapter) or generate + push for Drizzle/Prisma
4. Verify: check that twoFactorSecret column exists on user table

import { betterAuth } from "better-auth";
import { twoFactor } from "better-auth/plugins";

export const auth = betterAuth({
  appName: "My App",
  plugins: [
    twoFactor({
      issuer: "My App",
    }),
  ],
});

Client-Side Setup

import { createAuthClient } from "better-auth/client";
import { twoFactorClient } from "better-auth/client/plugins";

export const authClient = createAuthClient({
  plugins: [
    twoFactorClient({
      onTwoFactorRedirect() {
        window.location.href = "/2fa";
      },
    }),
  ],
});

Enabling 2FA for Users

Requires password verification. Returns TOTP URI (for QR code) and backup codes.

const enable2FA = async (password: string) => {
  const { data, error } = await authClient.twoFactor.enable({
    password,
  });

  if (data) {
    // data.totpURI — generate a QR code from this
    // data.backupCodes — display to user
  }
};

twoFactorEnabled is not set to true until first TOTP verification succeeds. Override with skipVerificationOnEnable: true (not recommended).

TOTP (Authenticator App)

Displaying the QR Code

import QRCode from "react-qr-code";

const TotpSetup = ({ totpURI }: { totpURI: string }) => {
  return <QRCode value={totpURI} />;
};

Verifying TOTP Codes

Accepts codes from one period before/after current time:

const verifyTotp = async (code: string) => {
  const { data, error } = await authClient.twoFactor.verifyTotp({
    code,
    trustDevice: true,
  });
};

TOTP Configuration Options

twoFactor({
  totpOptions: {
    digits: 6, // 6 or 8 digits (default: 6)
    period: 30, // Code validity period in seconds (default: 30)
  },
});