Search "SEO" in the Shopify App Store and you get hundreds of listings that all promise rankings. Ratings won't sort them, because a five-star image compressor and a five-star meta-tag editor do completely different jobs. Name the job first, then pick the app — and know up front that most SEO apps are tooling. They help you edit metadata, shrink images, or emit markup faster than doing it by hand, but you still do the strategy and the writing.
A second, smaller category does the work itself: generating content, hosting it, maintaining it, and measuring what it earns. Those are services with app-shaped billing, and they cost more because they replace hours rather than clicks. Comparing one against a low-cost metadata editor is a budgeting mistake in both directions. If you're weighing tooling against agencies or done-for-you services, start with what Shopify SEO actually costs.
One rule before any install: no app can fix a slow theme or thin content by itself. If your kitchenware store has three-sentence product descriptions, no meta-tag template rescues them. The jobs below run in rough priority order — content and speed problems outrank markup polish every time.