SiteLiner is a free tool by Copyscape/Screaming Frog that finds duplicate content, broken links, and internal link distribution across a website. StoreVitals monitors the full spectrum of ecommerce site health — SEO, security, performance, and accessibility — on an automated schedule.
SiteLiner and StoreVitals cover almost no overlapping ground. SiteLiner is the best free tool for detecting duplicate content and internal link distribution — two specific SEO issues that templated ecommerce sites (with hundreds of near-identical product pages) frequently need to audit. StoreVitals is a full ecommerce health monitor covering 20 technical checks across SEO, security, performance, and accessibility on a scheduled basis. Run SiteLiner once a quarter to audit duplicate content across your catalog; run StoreVitals weekly to catch broken links, security regressions, and new technical issues as they appear. They are complementary tools, not competing ones.