Case StudyTypeScript / Privacy / SSG / i18n

FormattedAI.pl

Free, privacy-first developer tools. 100% client-side -- zero uploads, zero tracking, zero accounts. Markdown formatter, AVIF converter, CSS/JS minifiers, SEO/GEO tag generator.

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FormattedAI.pl

FormattedAI is a collection of free, privacy-focused web tools for developers and content creators. Every tool runs entirely in the browser -- your data never leaves your device. No accounts, no uploads, no tracking.

The Problem

Every formatting and conversion tool on the market sends your data to external servers. For developers working under NDA or handling sensitive codebases, this is a direct violation of their agreements. Most tools also require accounts, track users with cookies, and serve ads.

I needed tools I could trust with client code, API keys visible in configs, and proprietary business logic. Nothing on the market offered that guarantee.

The Solution

A suite of 5 production tools (+ 2 coming soon) that run 100% in the browser. The server delivers static HTML, CSS, and JavaScript -- after that, your machine does all the work.

Tools

FormattedAI - Homepage

Homepage

Landing page with all available tools. Built with vanilla HTML/SCSS/JS, no frameworks.

1/6

Articles

A built-in knowledge base where I publish guides about web performance, image optimization, and the tools themselves. Serves as both documentation and a content hub for organic traffic.

FormattedAI - Articles section

Technical Architecture

The entire application is built with vanilla HTML, SCSS, and JavaScript -- no frameworks. Build tools are limited to Sass, esbuild, and a custom Node.js i18n generator. This keeps the bundle tiny and eliminates supply chain risk.

  • No frameworks -- pure HTML/SCSS/JS, zero runtime dependencies
  • WebAssembly -- AVIF conversion uses jSquash WASM encoder running in the browser
  • Client-side libraries -- Terser, CSSO, and Beautify bundled for in-browser minification/formatting
  • Marked + DOMPurify -- Markdown parsing with HTML sanitization
  • Static i18n -- custom build script generates separate HTML for Polish and English from JSON locale files and templates
  • Nginx -- production deployment with gzip, 1-year asset cache, security headers

SEO and GEO

The SEO/GEO Tag Generator is not just a tool -- FormattedAI itself is optimized for both traditional search and AI engines:

  • JSON-LD structured data (WebSite, WebApplication, FAQPage, BreadcrumbList)
  • Open Graph + Twitter Card meta tags on every page
  • Hreflang alternates for PL/EN
  • llms.txt for AI crawler discoverability
  • AI-aware robots.txt (GPTBot, ClaudeBot, PerplexityBot)

Stack

  • Vanilla HTML / SCSS / JavaScript (no frameworks)
  • esbuild + Dart Sass (build only)
  • WebAssembly (jSquash AVIF encoder)
  • Terser, CSSO, js-beautify (bundled for client-side)
  • Marked + DOMPurify (Markdown processing)
  • Custom Node.js i18n static generator
  • Nginx (production server)

Results

  • 100/100 Lighthouse score across all pages
  • Zero external API calls -- everything runs locally
  • 2 languages -- full Polish and English, statically generated
  • 5 live tools + 2 coming soon (JSON Formatter, Color Palette)
  • MIT licensed -- fully open-source
  • Used by developers in companies with strict data handling policies