FX Checker — a dark-themed live currency converter with ECB/EOD data

Design Documentation

Architecture, technical decisions, and implementation details.

Architecture

How a frontend-only converter stays loop-free, cache-polite, and keyboard-complete — layers, request flow, and the two-way protocol.

Updated August 2026

Functional Requirements

What the app must do, in plain language.

Updated August 2026

Architecture Decisions

Four key choices and why they were made.

Updated August 2026