Scott Bolinger

GTINs (Global Trade Item Numbers) including UPC, EAN, and ISBN are globally recognized unique identifiers for products.
They are required to list your product on Google and Amazon, this plugin allows you to add your GTIN and display it on your product page.
Supports:
<ul>
<li>Simple products</li>
<li>Variable products</li>
<li>Composite products</li>
<li>Product bundles</li>
</ul>
Features:
<ul>
<li>Add GTIN for main product</li>
<li>Add unique GTINs for product variations</li>
<li>Option to display GTIN on the single product page</li>
<li>Change GTIN to any other text</li>
<li>Add GTIN to structured product data</li>
<li>Works with product feeds like Google Shopping and more (requires a feed plugin)</li>
</ul>

WooCommerce UPC, EAN, and ISBN

Awesome plugin with great code

Add GTIN codes like UPC, EAN, and ISBN to your WooCommerce products.

JS Morisset

Provides additional fields in the WooCommerce “Product data” metabox and under the product webpage “Additional information” section:
<ul>
<li>MPN (Manufacturer Part Number)</li>
<li>ISBN</li>
<li>GTIN-14</li>
<li>GTIN-13 (EAN)</li>
<li>GTIN-12 (UPC)</li>
<li>GTIN-8</li>
<li>GTIN</li>
<li>Net Length / Depth</li>
<li>Net Width</li>
<li>Net Height</li>
<li>Net Weight</li>
<li>Fluid Volume</li>
</ul>

The SSO > WC Metadata settings page allows you to enable or disable each product metadata (aka custom field), along with customizing the label and placeholder values for the available languages (aka WordPress locales).
The product global identifier values (ie. MPN, ISBN, GTIN-14, GTIN-13, GTIN-12, GTIN-8, and GTIN) are searchable from both the front-end webpage, and the admin WooCommerce Products page.
The WPSSO Schema Product Metadata for WooCommerce add-on provides Schema (aka Schema.org) mpn, gtin14, gtin13, gtin12, gtin8, gtin, productID isbn, depth (aka length), width, height, weight, and additionalProperty fluid_volume values to the <a href="https://wordpress.org/plugins/wpsso/" rel="ugc">WPSSO Core plugin</a> for Google Rich Results, Rich Snippets, and Structured Data.
<h3>Includes WooCommerce Fluid Volume Units</h3>
Includes a Fluid volume unit option in the WooCommerce > Settings > Products settings page:
<ul>
<li>ml</li>
<li>cl</li>
<li>l</li>
<li>US tsp</li>
<li>US tbsp</li>
<li>US fl oz</li>
<li>US cup</li>
<li>US pt</li>
<li>US qt</li>
<li>US gal</li>
</ul>
<h3>Additonal Meta Tags and Schema Markup</h3>
Automatically provides additional Open Graph product meta tags for enabled product metadata:
<ul>
<li>product:ean</li>
<li>product:isbn</li>
<li>product:mfr_part_no</li>
<li>product:upc</li>
<li>product:weight:value</li>
<li>product:weight:units</li>
</ul>
Automatically provides additional Schema Product and Offer properties for enabled product metadata:
<ul>
<li>mpn</li>
<li>gtin14</li>
<li>gtin13</li>
<li>gtin12</li>
<li>gtin8</li>
<li>gtin</li>
<li>productID isbn</li>
<li>depth (aka length)</li>
<li>width</li>
<li>height</li>
<li>weight</li>
<li>additionalProperty fluid_volume</li>
</ul>
<h3>WPSSO Core Required</h3>
WPSSO Schema Product Metadata for WooCommerce is an add-on for <a href="https://wordpress.org/plugins/woocommerce/" rel="ugc">WooCommerce</a> and the <a href="https://wordpress.org/plugins/wpsso/" rel="ugc">WPSSO Core plugin</a>, which creates extensive and complete structured data to present your content at its best for social sites and search results – no matter how URLs are shared, reshared, messaged, posted, embedded, or crawled.

WPSSO Schema Product Metadata for WooCommerce

MPN, ISBN, GTIN, GTIN-8, UPC, EAN, GTIN-14, net dimensions, and fluid volume for WooCommerce products and variations.

WooCommerce UPC, EAN, and ISBN vs WPSSO Schema Product Metadata for WooCommerce