04 / 2025–2026
Výpočtář
A searchable portal with 122 practical calculators and converters across 11 categories, built around a consistent interface and connected tools.
01
What it solves
Výpočtář brings financial, mathematical, technical and everyday calculations into one searchable product. Individual calculators stay focused while categories, search and related tools make the wider collection easy to navigate.
02
My work
I designed and implemented the product structure, calculation logic, forms, search, responsive interface and Czech/English localization. The rebuild also covered external data sources, automated testing and technical SEO.
How the product is built
122 tools, one system
The main parts of the product.
- 122 calculatorsPractical calculations across 11 categories122 tools
- 11 categoriesFinance, maths, technical work and everyday use122 tools
- SearchA fast path to a specific calculationSearch
- CZ / ENSeparate localized URLs and contentLocalization
- Related toolsConnected calculators by contextSearch
- ValidationInput checks, methodology and limitsAutomated tests
- Automated testsCalculations kept outside the UI and covered by testsAutomated tests
- Technical SEOCanonical URLs, sitemap, structured data and IndexNowTechnical SEO
03 · Principle
Each calculator does one job.
Each calculator handles one clear task from input to result. Methodology, examples, validation and related tools provide context without getting in the way of the calculation.
04 · Implementation
Calculation is separate from the form.
Calculation logic is separate from presentation components. A shared calculator structure handles inputs, validation, metadata and localized content, while currency conversion uses Czech National Bank daily rates and an explicit state when that source is unavailable.
Technical details
Project structure
- 122 toolsShared architecture for calculators across 11 categories
- SearchSearch, categories and related tools
- Separated logicCalculations and validation outside the presentation layer
- LocalizationSeparate Czech/English structure, metadata and hreflang
- External dataCzech National Bank rates with explicit handling when the source is unavailable
- Automated testsCalculations, routes, SEO and build
- Technical SEOCanonical URLs, sitemap, structured data and IndexNow
- Next.js 14
- React 18
- TypeScript
- Tailwind CSS 3.4
- Lucide React
- Vitest
- Playwright
- ČNB