Currency Converter App Project Report
1. The Concept
Currency Converter App is a bilingual currency-converter web app designed primarily for Cambodian workers and students living in Japan. It helps users quickly convert Japanese Yen into Cambodian Riel, US Dollars, and other international currencies.
The project focuses on speed and simplicity. Users can enter an amount, select two currencies, and see the converted value immediately. Currency Converter App is only a conversion tool—it does not exchange, store, send, or receive real money.
2. The Stack
The Stack: HTML5, CSS3, JavaScript, Local Storage, Exchange Rate API, and responsive web design.
The application uses open.er-api.com to retrieve exchange rates. Local Storage saves the selected language, favorite currency pairs, conversion history, and cached rates.
The AI Assist: Codex helped plan the product, identify the target audience, design the bilingual UI/UX, create the conversion logic, connect the exchange-rate API, debug responsive-layout issues, manage local currency flags, and remove unused assets and code.
3. The 1 Day Sprint
Morning (Hours 1–3): Defined the main concept, target audience, and project scope. The primary audience was narrowed to Cambodian workers and students living in Japan. The core requirements included Khmer and English support, JPY-to-KHR conversion, quick amount buttons, and a mobile-first interface.
Afternoon (Hours 4–6): Developed the main converter using HTML, CSS, and JavaScript. Added currency selection, automatic conversion, currency symbols and codes, local flag assets, favorites, history, copy and share actions, language switching, and online/offline exchange-rate handling.
The Finish Line (Hours 7–8): Improved the responsive layout based on visual testing. Fixed overlapping content and scrolling problems, sorted currencies alphabetically, added three rotating currency suggestions, prevented identical currency pairs, removed unnecessary PWA files, and cleaned unused CSS.
4. The Roadblocks
Roadblocks: The main challenge was fitting all important content onto small mobile screens without creating excessive scrolling. Some panels and action buttons initially overlapped other content on short screens.
Another challenge was keeping exchange-rate information understandable without making users think Currency Converter App could transfer real money. The wording and interface were adjusted to clearly present the app as a reference-only currency converter.
External flag images were also a potential reliability problem, so the flags were stored locally. Browser caching and the previous Service Worker occasionally displayed older versions of the interface, requiring cache cleanup after updates.
5. Key Takeaways
A focused product is more useful than an application filled with unrelated features. Currency Converter App works best when its main purpose—fast currency conversion—is immediately clear.
Designing for mobile screens requires prioritizing essential information and testing on different viewport heights. The main conversion should remain visible and understandable within three seconds.
Local assets improve reliability, while clear currency symbols, codes, timestamps, and status indicators increase user confidence.
Bilingual support is an important part of the product rather than an optional extra because the target audience uses both Khmer and English.
User feedback and screenshots were valuable for identifying layout and usability issues that were not obvious during the initial implementation.
My final thought: Currency Converter App demonstrates how a small, clearly targeted web app can solve a real everyday problem. Its strongest qualities are simplicity, accessibility, and a design created specifically for Cambodian users living abroad.