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Juan José Peña Delgado
Juan José Peña Delgado

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How I Built a 2,600-Page Unit Converter with Programmatic SEO

#webdev #javascript #seo #productivity

I recently launched Qvert — a free unit conversion website with 2,600+ pages, each targeting a specific conversion pair like "centimeters to inches" or "USD to EUR."

The Problem

Every unit converter I used was either:

  • Slow — heavy JavaScript bundles, multiple seconds to load
  • Cluttered — walls of ads before you can even find the input
  • Limited — one generic converter page for everything

I wanted something fast, clean, and comprehensive.

The Approach: Programmatic SEO

Instead of building one converter page with dropdowns, I generated a dedicated page for every conversion pair. Each page has:

  • Its own URL (/length/cm-to-inch)
  • Unique meta title and description
  • A reference table with common values
  • AI-generated content tips (context, use cases, fun facts)
  • FAQ section with structured data
  • Visual comparison tools

With 15 unit categories and hundreds of units, this generates 2,600+ unique pages — each one an entry point for organic search.

Key Features

Smart Search

Users can type naturally: "175 cm in inches" or "how many cups in a gallon." The parser uses scored matching to find the right conversion:

  • Exact match gets highest priority
  • Prefix matching scores next
  • Substring matching is a fallback

This prevents common mistakes like "meters" accidentally matching "millimeters."

Visual Comparisons

Instead of just showing numbers, Qvert has interactive visualizations:

  • Dual rulers — two rulers with different scales side-by-side, with markers showing where a value lands on each
  • "How many fit?" dot grid — animated dots showing how many target units fit in the source value
  • Thermometers — for temperature conversions, dual thermometers with color coding from blue (cold) to red (hot)

Currency with Live Rates

29 world currencies with rates updated daily. The rates are fetched at build time, so there's zero runtime API cost — the conversion factors are baked directly into the pages.

Embeddable Widgets

Any conversion can be embedded on other sites with a single line of code:

<iframe src="https://qvert.ai/embed/length/cm-to-inch" 
        width="450" height="230" frameborder="0">
</iframe>
Enter fullscreen mode Exit fullscreen mode

This drives traffic back to Qvert while providing value to other site owners.

Content Strategy

Each page needs to be unique for SEO. I used AI to generate:

  • Context tips — "1 meter is about the height of a kitchen counter"
  • Use cases — "Commonly used by travelers converting luggage weight limits"
  • Fun facts — "The metric system was introduced during the French Revolution"

This content is generated once at build time, so there's no per-request API cost.

Results

  • 2,600+ pages across 15 categories
  • Pages load in under 50ms
  • Each page is under 30KB
  • Submitted to Google Search Console with XML sitemap
  • Structured data: FAQPage, HowTo, BreadcrumbList schemas

What I Learned

  1. Programmatic SEO works — generating thousands of pages from data is a powerful strategy for long-tail keywords
  2. Unique content matters — Google needs each page to offer something different, not just a different number in the same template
  3. Speed is a feature — when your competition takes 3 seconds to load, loading in 50ms is a genuine differentiator
  4. Visual tools add value — the ruler and dot grid visualizations are what users remember and share

Try It

Check out Qvert — convert anything instantly. The embeddable widget is free for anyone to use.

What would you add? Let me know in the comments.

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