Nest Angular Cryptocurrency API

Overview

The Nest Angular Cryptocurrency API is a real-time crypto price tracker built with Nest.js and Angular. The app fetches and displays cryptocurrency prices from an external API, updating every two seconds using a custom server polling engine powered by RXJS. The project focuses on pure logic and reactive programming, avoiding LLMs or wrappers for a clean, maintainable architecture as it was built prior to the generative AI revolution.

Features

• Real-Time Prices: Fetches and displays live cryptocurrency prices with a two-second polling interval.
• RXJS Polling Engine: Uses interval and switchMap operators to manage API requests and prevent race conditions.
• Angular Frontend: Responsive UI for viewing price data.
• Nest.js Backend: Handles API requests and environment configuration.
• Environment Config: Easy setup with .env files for API keys and endpoints.

Tech Stack

• Backend: Nest.js (Node.js)
• Frontend: Angular
• Reactive Programming: RXJS

Challenges

The main challenge was building a robust polling engine that could handle frequent updates without causing race conditions or memory leaks. Leveraging RXJS’s interval and switchMap operators provided a clean solution for managing asynchronous data streams. Ensuring smooth integration between the Nest.js backend and Angular frontend required careful API design and environment management.

Lessons Learned

This project reinforced the power of reactive programming for real-time applications. By focusing on pure logic and leveraging RXJS, it’s possible to build efficient, maintainable polling systems without unnecessary complexity.