Shipping Rates Spreadsheet stores a country (and, in Pro, region and currency) price table on each WooCommerce shipping method instance and applies those prices at checkout.
Use the plugin’s own Shipping Rates Spreadsheet method in a shipping zone, or attach the same matrix to existing methods (Flat Rate, local pickup, carrier plugins, and similar).
Matrix data lives in WooCommerce shipping method instance settings. The plugin does not create custom database tables.
Product page: https://devstudio8848.com/shipping-rates-spreadsheet/
The matrix editor in the admin uses two bundled MIT-licensed libraries, shipped unmodified:
Versions, licenses, and links to the non-minified sources are also listed in assets/vendor/README.md.