Watchthis.dev

This platform is a free JavaScript SEO checker that compares the HTML a server sends with the page after JavaScript has run. It is meant to show developers and SEO specialists which content search engines and AI crawlers may miss. A user enters a public URL and the tool fetches the raw HTML response, renders the same page in a real Chromium browser, waits for the DOM to settle, and compares the two versions. Most checks finish in 20 to 30 seconds. The report flags title, meta description, canonical and robots tags that appear only after rendering, headings, links and text that are missing from the initial HTML, structured data added on the client, JavaScript runtime errors, redirect chains, and differences in internal link counts. Findings carry severity levels and a health score. The site also hosts guides on JavaScript SEO for React, Next.js, Vue and Angular. The tool is built by Prime Digital, a Canada based SEO and web development company, and is described as open source. The vendor states that it is a diagnostic aid and not an exact replica of Google Search infrastructure. The tool is free and requires no signup. The site shows no paid plans.