Ravi Kiran Katha

WordPress has a site-level timezone setting configured from the admin back-end. All dates and times displayed on the front-end are typically displayed in this timezone.
This plugin enables the display of dates/times in the front-end using the browser’s timezone. This is done by overriding the WordPress’s ‘timezone_string’ and ‘gmt_offset’ options to match the user’s timezone for the duration of a particular request 
ONLY on the front-end interface.
<h4>Browser Timezone Detection</h4>
The browser’s timezone is detected using one of the following two methods
<ol>
<li><a href="http://pellepim.bitbucket.org/jstz/" rel="nofollow ugc">jsTimezoneDetect</a> (default)</li>
<li><a href="http://caniuse.com/geolocation" rel="nofollow ugc">HTML5 Geolocation API</a> and <a href="https://developers.google.com/maps/documentation/timezone" rel="nofollow ugc">Google Timezone API</a></li>
</ol>
jsTimezoneDetect (default) 
 This is the default timezone detection mechanism. Please refer to the script <a href="http://pellepim.bitbucket.org/jstz/" rel="nofollow ugc">home page</a> 
for the compatibility and other notes
HTML5 Geolocation API 
 Detects the current geo-location using <a href="http://caniuse.com/geolocation" rel="nofollow ugc">navigator.geolocation.getCurrentPosition</a>. The location thus detected will be sent to the <a href="https://developers.google.com/maps/documentation/timezone" rel="nofollow ugc">Google Timezone API</a> 
which returns the timezone id – similar to “Asia/Kolkata”.
This method requires you to
<ul>
<li>Enable the “Google Timezone API” option on the plugin options page</li>
<li>Specify a valid <a href="https://developers.google.com/maps/documentation/timezone/get-api-key" rel="nofollow ugc">Google API Key</a>
<ul>
<li>The key should be a browser key</li>
<li>The “Accepted HTTP Referrers” should include the domain name used by the hosting wordpress site or left blank to allow all referrers</li>
</ul>
</li>
</ul>
If the required options for the usage of Google Timezone API are not met, the detection mechanism falls back to the default one.
<h4>Post Timezone Detection</h4>
<ul>
<li>If the browser’s timezone id is not detected successfully, everything else behaves as if this plugin is not installed.</li>
<li>If the browser’s timezone id is detected, the following actions take place
<ul>
<li>A cookie will be set in the browser, based on the cookie options specified on the plugin options page</li>
<li>If a cookie already exists previously with the same id, no action is taken</li>
<li>If a cookie doesn’t already exist previously or exists with a different timezone id, then a window.reload is triggered to refresh the page so that the dates/times on the page are updated</li>
</ul>
</li>
</ul>
<h4>EventON Hook</h4>
This plugin provides a feature to hook into the EventON plugin. When enabled, all EventON dates/times are updated to reflect the browser’s timezone.
<h4>Shortcodes</h4>
This plugin defines the below shortcodes
<ol>
<li>[wp_user_timezone_id] => Returns the timezone id of the browser or null if not available.</li>
<li>[wp_user_timezone_offset] => Returns the timezone’s gmt offset in hours of the browser or null if not available.</li>
</ol>
<h4>Options</h4>
This plugin defines the below options to retrieve the original timezone_string and gmt_offset defined at the site level
<ol>
<li>get_option( ‘site_timezone_string’ ) => Returns the original timezone_string option for the site</li>
<li>get_option( ‘site_gmt_offset’ ) => Returns the original gmt_offset option for the site</li>
</ol>
<h4>Actions/Hooks</h4>
This plugin defines the below filters/hooks
<ol>
<li>apply_filters( ‘wp_user_timezone_id’, $tz_id ) => Allows you to override the timezone string determined by the plugin. This filter can be used to apply user’s timezone preference. If any plugin or wordpress core implements a feature to accept and store user’s preferred timezone, the ‘wp_user_timezone_id’ can be used to apply that timezone value to the front-end. Reference: <a href="https://core.trac.wordpress.org/ticket/18146" rel="nofollow ugc">Add user-level timezone setting</a>).</li>
</ol>
<h4>Admin Backend Dates/Times</h4>
Important: The admin back-end is not modified by this plugin. All dates/times displayed in the back-end are still in the original timezone specified by the WordPress General Settings.

WP User Timezone

Magnificent

WP User Timezone displays the front-end dates & times in the browser's local timezone without actually modifying your database.

Amin Raoufi

Admin Toolbar Live Clock keeps the current time and date always in view while you work in wp-admin.
It’s ideal for editors and admins who constantly check scheduled content, cron jobs, moderation timestamps, or who manage sites across different time-zones.
<blockquote>
Designed for daily professional use: lightweight, clean UI, no clutter — and optional “Minimal mode” when you want the plugin at its simplest.
</blockquote>
<h3>Who benefits?</h3>
<ul>
<li>Editors coordinating global content releases</li>
<li>Support agents logging activity against a consistent time source</li>
<li>Developers verifying scheduled tasks (WP-Cron / Action Scheduler)</li>
<li>Multisite admins overseeing sites across regions</li>
</ul>
<h3>Feature highlights</h3>
<ul>
<li>Live ticking — updates every second (no page reloads, no Ajax polling)</li>
<li>Display modes — choose Digital or the new Analog clock mode</li>
<li>Analog clock (new)
<ul>
<li>Multiple themes (including Tomanify)</li>
<li>Size options (Small / Large)</li>
<li>Optional date display inside the analog face</li>
</ul>
</li>
<li>Floating clock (new) — show the clock as a floating widget in wp-admin
<ul>
<li>Analog mode uses the floating view automatically</li>
</ul>
</li>
<li>Draggable position (new) — drag the floating clock and it remembers its position for next visits</li>
<li>Minimal mode (new) — disables advanced styling/options and keeps only the core settings</li>
<li>Calendars — Gregorian, Persian (Jalali), Islamic (Hijri), Hebrew, Buddhist (Thai) and Japanese</li>
<li>Plugin language — choose the plugin language independently from the WordPress site language
<ul>
<li>Languages bundled – en_US, fa_IR, ar, es_ES, fr_FR, he_IL, hi_IN, ja, th_TH, de_DE, ru_RU, tr_TR, ps_AF, uk_UA, pl_PL, ro_RO, zh_CN, ko_KR (+ fully translatable via PO/MO)</li>
</ul>
</li>
<li>Time formats — 12-hour or 24-hour</li>
<li>Timezone — use the site timezone or pick any IANA timezone</li>
<li>Colour controls — clock & date colours (where applicable)</li>
<li>Tabbed settings UI (new) — cleaner settings screen with General / Style / About</li>
<li>Admin-only — visible only in wp-admin (never on the front-end)</li>
<li>Clean uninstall — removes plugin options on Delete via <code>uninstall.php</code></li>
</ul>
Find the settings page at Settings → Toolbar Clock.
<h3>Author</h3>
Developed by Amin Raoufi.

Admin Toolbar Live Clock

Live clock for the WordPress admin bar with multi-calendar, per-user timezone, and optional analog & floating modes.

WP User Timezone vs Admin Toolbar Live Clock