I need a small-footprint crypto converter that takes an entered amount and instantly shows its value in another coin using up-to-the-second market data. The core requirement is accuracy: the moment a user clicks “Convert”, the rate should be pulled from a reliable API such as CoinGecko, CoinMarketCap, or another source you prefer, with no noticeable lag. I’m open on platform. A single-page web app, a lightweight desktop widget, or even a slim mobile build are all fine as long as the code is clean, well-documented, and easy for me to extend later (for example, adding new pairs or styling changes). Deliverables • Working converter supporting at least the major pairs (BTC, ETH, LTC to start). • Source code and any build scripts. • A concise README covering set-up, API keys, and how to swap in new coins. • Brief note on how you manage API rate limits and caching so results stay fast and dependable. If your stack choice, timeframe, or deployment approach improves performance or simplifies maintenance, let me know—flexibility here is a plus.