Product Comparison Widget Needed for Online Store

We run an online store and want to add a comparison tool that helps customers choose between similar products faster. Right now people open several product pages in separate tabs and manually scroll back and forth to compare specifications, which is slow and often leads them to abandon the purchase decision altogether. We are looking for a developer who can design and implement a widget that solves this properly.

The core idea is simple: a button on every product card lets a shopper add that item to a comparison list, and a separate page or slide-out panel then shows the selected products side by side in a characteristics table. Rows that differ between models should be visually highlighted so the customer can immediately spot what actually changes from one option to another, instead of reading through a wall of identical specs. The widget needs to remember the selection while the shopper keeps browsing, work smoothly on mobile screens, and integrate cleanly with our existing product catalog and attribute structure.

We would like to discuss the exact list of features, the data source for specifications, and the visual design before development starts. Please share examples of similar widgets you have built along with your estimate for timeline and cost.

Key requirements:
— add to comparison directly from the product card, with a visible counter
— responsive comparison table with sticky headers and highlighted differences
— ability to remove single items and clear the whole list
— reasonable performance for products with many attributes