The best SEO tool for Shopify depends on what you're fixing. Shopify's built-in SEO is weak—limited control over URLs, auto-generated canonical tags, and bloated theme code—so you need external tools to fill gaps. For on-platform fixes, Shopify apps like Plug in SEO (CAD $20–30/month) or SEO Manager handle basics: alt text audits, meta tag templates, and broken link checks. They integrate directly with your store and flag low-hanging fruit. Avada SEO Suite is another option if you want image compression and speed tweaks bundled in, though it can slow admin panels on larger catalogs. Pair any app with Google Search Console—it's free and shows you exactly which product pages Google is indexing, which have mobile issues, and where your click-through rates are tanking. For Shopify stores, GSC often reveals duplicate content from collection pages or variant URLs that apps miss. For technical audits, use Screaming Frog (free up to 500 URLs, £149/year for unlimited) or Sitebulb. Crawl your site monthly to catch orphaned products, redirect chains from deleted collections, or hreflang errors if you run multi-currency markets. Shopify's liquid templating creates odd edge cases—like pagination parameters that waste crawl budget—and desktop crawlers catch those. Keyword research tools like Ahrefs or SEMrush work for Shopify the same as any platform, but they're overkill if you're just starting. Use Google Keyword Planner or Ubersuggest to map commercial intent keywords to product categories, then validate search volume in your actual GSC data after six weeks. At Ottawa SEO, we run Screaming Frog audits on Shopify clients every quarter and use GSC weekly for performance tracking. Apps handle the repetitive stuff—meta tags, image alt text—but they won't tell you why your site speed is 4.2 seconds or why Google isn't indexing your size-variant pages. You need a crawl tool for that. Budget CAD $50–200/month total if you're serious: one Shopify app, one crawl tool license, and GSC for free.