With this pluging you can add a countdown to your blog. Just specify an end-date in the settings (backend) and put one single line of php-code somewhere you want this countdown to be displayed. This plugin uses the ajax-technology for updating the countdown every second. The moment you change the specified date in the settings, the plugin recognizes this change and updates itself according to the new date.

COUNTdown

This plugin allows you to add an ajax-updated countdown to your blog.

ujimoto

Uji Countdown lets you display eye-catching countdowns anywhere on your site. Drop the block or shortcode into a post, page, widget, or template and fine-tune every detail—colours, labels, animation, server vs. visitor time and more.
<h3>Key features</h3>
<ul>
<li>Block Editor support – create and preview timers visually. </li>
<li>Recurring & repeat timers – perfect for evergreen offers. </li>
<li>Unlimited styles with colour & size controls. </li>
<li>Switch between server time or visitor time. </li>
<li>Translate date labels and numeric separators. </li>
<li>Optional redirect or hide when the timer expires. </li>
<li>Widget area & shortcode support. </li>
<li>Multi-language date formats. </li>
<li>Pro only: responsive layouts, multiple timers per page, circular timer add-on.</li>
</ul>
<a href="https://wpmanage.com/project/ujicountdown/" rel="nofollow ugc">Demo site</a>
<h3>Support</h3>
Need help? Email info@wpmanage.com or open a topic on the support forum.

Uji Countdown

A fully-customizable HTML5 countdown timer with Block Editor support.

COUNTdown vs Uji Countdown