In Stock Checkbox
Adds in-stock checkbox into the search form

The By In Stock extension adds a checkbox or switcher to filter products by stock status. It supports two modes: "In stock" (hides out-of-stock products) and "Out of stock" (shows only out-of-stock products). For variable products, it queries the wc_product_attributes_lookup table for accurate per-variation stock status detection, ensuring that a variable product with at least one in-stock variation is correctly shown when filtering for in-stock items.
How to use
Enable "By In Stock" in the WOOF settings panel. A stock status filter will appear in the filter form. Toggle between showing only in-stock or only out-of-stock products.