habibiplugins

Checkout Simulator for WooCommerce helps store owners and developers preview how checkout behaves before a customer pays. Build a test cart, apply coupons, pick a shipping address, and see which shipping zone matches, available shipping methods and rates, payment methods, and cart totals – plus context when rules interact (for example, a coupon changing free-shipping eligibility).
Perfect when you want to:
<ul>
<li>Debug shipping zones and location rules without guessing from the storefront</li>
<li>Validate shipping methods and rates for a given address</li>
<li>Check coupon + shipping interactions on a realistic cart</li>
<li>See payment methods that would appear for the simulated checkout context</li>
<li>Explain “why” something matched (zone match reasoning) to support clients</li>
</ul>
How it works
<ul>
<li>Add products (search + quantity) and optional coupon codes</li>
<li>Choose a preset test address or enter country, state, and postcode manually</li>
<li>Click Simulate to run WooCommerce’s logic</li>
</ul>
<h3>Configuration</h3>
<ul>
<li>Products: Use the product search to add one or more products and set quantities. Leave empty to only look up the shipping zone and methods for the address (no cart totals).</li>
<li>Coupon codes: Enter comma-separated codes; they are applied during simulation when products are present.</li>
<li>Shipping address: Select a preset (e.g. US – California) or choose “Enter manually” and fill Country, State/County, and Postcode.</li>
<li>Access: Only users with the <code>manage_woocommerce</code> capability can open the Checkout Simulator (typically Administrators and Shop Managers).</li>
</ul>

Checkout Simulator for WooCommerce

Preview WooCommerce checkout in the admin: zones, shipping, coupons, payments, and totals. No order placed; all on your server.

gr8nilay

This plugin create a custom post type for coupon code that includes Coupon Start / End date, Discount in Percentage / Cash. The coupons are listed with all details so you can easily manage it from listing page. You can easily use this plugin by customization by your own to enable coupon feature to your site.
How to Use: 
This is custom post type so you can apply all the hooks / customization that you do with any custom post type. Below are the variables which are used to store values of coupons so you just need to use meta values for the same.
Coupon Code = np_ccode__ccode 
Discount In ( % or $ ) = np_ccode__discount_in 
Discount Amount/Percent = np_ccode__amt_per 
Coupon Start Date = np_ccode__ccstart_date 
Coupon End Date = np_ccode__ccstart_date
You can use above meta keys into your site by your own to customize your site coupon feature.

Easy Coupon Code WP

Nice..!!

Provides you the custom post type with ready meta fields to enable coupon module to your site.

Checkout Simulator for WooCommerce vs Easy Coupon Code WP