Richard Palethorpe

Provides a block which embeds a <a href="https://dobu.uk" rel="nofollow ugc">DoBu.uk availability calendar and enquiry form</a> 
for a given nick name.
See the above link for a demonstration.

DoBu.uk Availability

Embed DoBu.uk availability and booking calendars

bobvanoorschot

This is used with the bukazu bookings system, you need to have an account with <a href="https://bukazu.com/" title="Your favorite booking software" rel="nofollow ugc">BUKAZU</a>
The plugin includes a Gutenberg block, <code>bukazu/portal</code>, for embedding the Bukazu portal directly in the block editor without using a shortcode.
The preferred integration method is the Gutenberg block. Use the shortcode only when you need to support classic editor or template-based integrations.

Bukazu Search Widget

Create a simple search widget for bukazu search calendar

DoBu.uk Availability vs Bukazu Search Widget