Free SEO Checker
An open-source on-page SEO checker that scores any page out of 100 across metadata, structure, structured data, indexing and keyword placement, with a fix for each issue.
Live deployments
Source repositories
Project overview
Paste a URL and get a weighted SEO score with plain-English fixes. A small Cloudflare Worker fetches the page once, because browsers cannot read other sites’ HTML. The browser then runs 22 checks against that snapshot: title and description length, heading outline, content depth, alt text, links, JSON-LD, Open Graph, noindex, canonical, HTTPS, redirects, robots.txt, the sitemap and server response time.
What I built
- 01
Wrote a Cloudflare Worker that fetches a page with a manual redirect chain, then returns headers, timing, HTML, robots.txt and sitemap status.
- 02
Locked the Worker down against misuse: public hosts only, no IP literals, per-IP rate limiting, a 2 MB cap and a 10-minute edge cache.
- 03
Built the scoring engine as plain TypeScript running on the browser’s own DOM parser, with weights that put crawl blockers first.
- 04
Parsed robots.txt per user-agent group, so a rule for one bot is not mistaken for a site-wide block.
Implementation notes
The same engine powers the tool on this site and the standalone GitHub Pages build; the Worker can be self-hosted on Cloudflare’s free plan.
It reports what is on the page. Ranking positions need Search Console or paid SERP data, and the tool says so instead of guessing.
Technology stack
- TypeScript
- Cloudflare Workers
- Vite
- DOMParser
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