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From Spreadsheet to SaaS: How I Built a Free Landing Page SEO Checker in a Weekend

#seo #webdev #saas #cloudflare

I've been building SaaS tools for a while now, and one pattern I keep seeing is this: developers spend weeks perfecting their product, then launch a landing page that nobody visits. Not because the product is bad — because the page itself has basic SEO issues that prevent it from ranking.

So I did what any developer would do: I built a tool to fix it.

The Problem: Launching Blind

When I was preparing to launch my first SaaS product, I ran my landing page through every SEO tool I could find. The free ones gave you 3-5 checks before asking you to pay. The paid ones cost $99+/month for features I didn't need.

All I wanted was a quick sanity check:

  • Does my page have proper meta tags?
  • Is the heading structure correct?
  • Are there missing Open Graph tags for social sharing?
  • Is the page mobile-friendly?
  • Does the sitemap exist?

Simple questions. But no free tool gave me straight answers without a signup wall.

The Weekend Build

I decided to build my own using Cloudflare Workers. Here's the tech stack:

  • Cloudflare Workers — Edge computing, no server to manage, generous free tier
  • cheerio — HTML parsing (works in Workers)
  • Hono — Lightweight web framework for Workers

The architecture is dead simple:

User submits URL
    → Worker fetches the page
    → Parses HTML with cheerio
    → Runs ~30 checks across 5 categories
    → Returns a scored report
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The 5 categories I check:

  1. Meta Tags — title, description, canonical URL, robots directives
  2. Open Graph — og:title, og:description, og:image, og:type
  3. Heading Structure — H1 exists, proper hierarchy, no skipped levels
  4. Performance Basics — image alt tags, viewport meta, charset declaration
  5. Technical SEO — sitemap.xml, robots.txt, HTTPS, mobile viewport

What I Learned Building It

1. Edge Computing Is Perfect for This

Cloudflare Workers run in 300+ locations worldwide. When someone submits a URL, the Worker fetches their page from the nearest point of presence. The whole check runs in under 2 seconds.

No server to provision. No database to maintain. Just a single JavaScript file deployed to the edge.

2. Most Landing Pages Fail the Same 5 Things

After testing hundreds of pages (mine and others'), the most common issues are:

  • Missing Open Graph tags — Your page looks terrible when shared on Twitter/LinkedIn
  • No sitemap.xml — Search engines can't discover your pages efficiently
  • Multiple H1 tags — Confuses search engines about your main topic
  • Images without alt text — Hurts accessibility and image search ranking
  • Missing canonical URL — Can cause duplicate content issues

These are all fixable in under 10 minutes. But most people don't know to check.

3. Free Tools Have a Place

I considered charging for this. But honestly? The value I get from driving traffic to my other tools is worth more than $5/month subscriptions.

The SEO checker is completely free. No signup. No credit card. No usage limits. Just paste your URL and get results.

The Tech Details (For Fellow Builders)

The core check logic is a series of functions that each return a score and a suggestion:

function checkMetaTags(doc, url) {
  const issues = [];
  const title = doc('title').text();

  if (!title) {
    issues.push({ severity: 'error', message: 'Missing <title> tag' });
  } else if (title.length > 60) {
    issues.push({ severity: 'warning', message: `Title too long (${title.length} chars, max 60)` });
  }

  // ... more checks
  return { score: calculateScore(issues), issues };
}
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Each check is independent, so adding new ones is trivial. I've been adding 1-2 new checks per week based on user feedback.

The frontend is vanilla HTML/CSS/JS — no React, no build step. It fetches the Worker endpoint and renders results client-side. Total bundle size: under 15KB.

What's Next

I'm considering adding:

  • Competitor comparison (check your page vs. a competitor's)
  • Historical tracking (see if your SEO score improves over time)
  • Specific suggestions with code snippets for each issue

But for now, it does one thing well: gives you a comprehensive SEO health check in seconds, for free.

Try It

The SEO Checker is live at: https://saaslaunch.dev/free-tools/seo-checker

Paste any URL, get your report. No signup, no email, no catch.

If you're about to launch a landing page, run it through this first. You might catch issues that would cost you organic traffic for months.

Full disclosure: I'm the developer behind this tool. It's part of SaaSLaunch, a collection of free pre-launch tools for indie developers. Feedback welcome — I read every comment.

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