Most of the time you don't choose. Paste a link and StockWatch works out what the shop runs on. When you do need to pick, these are the kinds:

• Shopify: most Pokemon TCG shops, hobby shops and independent brands run on Shopify. It can follow individual sizes and colours.
• WooCommerce: shops built on WordPress.
• Any other shop: for a shop that isn't one of the kinds we know. Paste its link and it works out how to read the page.
• Visual Selector: you point at the exact thing to watch on any page, such as a price, a sold-out button or a "coming soon" line. On a computer you click it with the Chrome extension. On a phone you tap it.
• Custom Website: the same idea done by hand, for people who are comfortable with CSS selectors.
• Named shops: Argos, Waterstones, Next, Primark and others each have a monitor made for that one shop.

Which plan has which

These are on every plan: Shopify Store, WooCommerce Store, Custom Website, Visual Selector, Next, Primark, SAP Commerce, Pokemon Center Drop Watchdog and Any other shop. Most of the other named shops need Standard or Power User.

The form puts a padlock on anything your plan doesn't include, and each shop's guide says which plan it needs. Browse them under Supported Sites on the Help home.