Shopify SEO apps fall into four categories, and only two of them are worth money for most stores.
Shopify handles canonicals, sitemaps and clean URLs natively, so apps claiming to fix those are selling you something you already have.
The categories that genuinely earn their fee are bulk metadata editing and structured data, because both are scale problems.
An SEO app that injects script into every page can cost you more in Core Web Vitals than it returns in rankings.
No app fixes thin collections, weak product data or an absent content strategy, and those are what actually hold most stores back.
Most stores do not need one to start. Shopify already generates sitemaps, sets canonical tags, produces clean URLs and serves over SSL.
The full guide has the formats, the deadlines and the worked examples.