Alessandro Raffa

In some cases you want your wordpress users to login with their email address instead of the username. To do this, you can use a good plugin like ‘WP Email Login’ or you can activate a ‘Register Plus Redux’ plugin’s option, but when the users will ask for lost password, the old / original username will be emailed to them, and this can cause confusion. To avoid this situation, just install and activate Login Email Sync, and it will sync the username ( user_login database field ) with the email ( user_email database field ) every time a user updates her/his profile.
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Login Email Sync

In some cases you want your wordpress users to login with their email address instead of the username. To do this, you can use a good plugin like &#03 …

oaron

OneCode Login provides a modern, passwordless authentication experience for your WordPress site. Instead of traditional passwords, users receive a secure 6-digit verification code via email.
<h4>Key Features</h4>
<ul>
<li>Passwordless Authentication – Users log in with just their email address</li>
<li>6-Digit Verification Codes – Secure, time-limited codes sent via email</li>
<li>Rate Limiting – Built-in protection against brute force attacks</li>
<li>Request ID Binding – Each code is bound to a specific login session for enhanced security</li>
<li>Neutral Feedback – Prevents user enumeration attacks by not revealing if an email exists</li>
<li>Customizable – Configure expiry times, cooldowns, and email templates</li>
<li>Accessible – Full keyboard navigation and screen reader support</li>
<li>Gutenberg Block – Easy to add login forms to any page</li>
<li>Shortcode Support – Use [onecode_login] anywhere</li>
<li>wp-login.php Integration – Optionally replace the default WordPress login</li>
<li>Developer API – Other plugins can use OneCode Login as an email one-time-code (OTP) service to verify a visitor’s email — see the Developer information section</li>
</ul>
<h4>Security Features</h4>
<ul>
<li>Cryptographically secure code generation</li>
<li>Codes and magic-link tokens are stored HMAC-hashed, never in plain text</li>
<li>Configurable code expiry (default: 10 minutes)</li>
<li>Resend cooldown to prevent spam</li>
<li>IP-based and email-based rate limiting</li>
<li>Automatic lockout after failed attempts</li>
<li>Codes are single-use and invalidated after successful login</li>
</ul>
<h4>Use Cases</h4>
<ul>
<li>Membership sites where password fatigue is an issue</li>
<li>Customer portals requiring simple authentication</li>
<li>Internal tools where security without complexity is needed</li>
<li>Any site wanting to improve user experience</li>
</ul>
<h3>Developer information</h3>
Other plugins on the same site can use OneCode Login as a generic email 
one-time-code (OTP) service — for example to verify a guest’s email before 
letting them act. OneCode emails the code and verifies it; your plugin keeps 
full control of its own login/session (OneCode only asserts that the code is 
valid for the email — it never logs anyone in). It works for any email 
address; the address does not need a WordPress account.
All entry points are plain functions (and matching filters), so you do not need 
a hard dependency on any class. The API is gated by the Settings → Advanced → 
Enable developer API toggle.
Detect support (side-effect free — never call the request hook just to probe):
<pre><code>if ( function_exists( 'onecode_login_request_otp' ) && onecode_login_supports( 'otp' ) ) { ... }
</code></pre>
<ol>
<li>
Start authentication — email a code and receive a handle:
$handle = onecode_login_request_otp( $email, array( ‘consumer’ => ‘my_plugin’ ) ); 
// $handle = array( ‘request_id’, ‘auth_secret’, ‘expires_in’ (seconds), ‘expires_at’ (UTC), ‘sent’ ) 
// On failure: a WP_Error (codes: disabled, invalid_request, rate_limited, cooldown).
</li>
</ol>
Keep <code>request_id</code> and <code>auth_secret</code> server-side (e.g. in a transient tied to the 
visitor). The <code>auth_secret</code> is NEVER shown to the customer — it is what stops an 
outsider who only knows the email from completing verification by guessing codes.
<ol>
<li>
Complete authentication — the customer gives your plugin the code from the email:
$result = onecode_login_verify_otp( array( 
 ’email’ => $email, 
 ‘request_id’ => $handle[‘request_id’], 
 ‘code’ => $code_from_customer, 
 ‘auth_secret’ => $handle[‘auth_secret’], 
 ‘consumer’ => ‘my_plugin’, 
) ); 
// Success: array( ‘valid’ => true, ’email’ => … ). Failure: WP_Error.
</li>
</ol>
On failure show a generic message to the user (the API intentionally returns a 
single <code>verify_failed</code> code so it can’t be used as an oracle).
Filters are also available for loose coupling: <code>onecode_login_request_otp</code> 
(<code>$pre, $email, $args</code>) and <code>onecode_login_verify_otp</code> (<code>$pre, $args</code>).
Discovery and capabilities:
<ul>
<li><code>onecode_login_supports( $feature )</code> — returns true for <code>'otp'</code>, 
 ‘identity_assertion’ and <code>'any_email'</code>.</li>
<li><code>onecode_login_api()</code> — returns the <code>OneCode_Login_API</code> service instance.</li>
<li><code>OneCode_Login_API::VERSION</code> — the API contract version (independent of the 
plugin version), so you can feature-gate against the API surface.</li>
<li><code>do_action( 'onecode_login_api_init', $api )</code> — fires once the API is ready; 
bind to it if you want to wire up as soon as OneCode Login loads.</li>
</ul>
Reference: <code>$args['consumer']</code> (a short <code>[a-z0-9_-]</code> label identifying your 
integration) is required on both calls — it isolates your codes and rate limits 
from the built-in login and from other consumers. Both request and verify are 
rate-limited by OneCode, returning <code>rate_limited</code> / <code>cooldown</code> WP_Errors you can 
surface to the user.

OneCode Login

Simple and secure passwordless login using email verification codes. No passwords to remember, just enter your email and verify with a 6-digit code.

Login Email Sync vs OneCode Login