The most challenging was the price monitoring app.

It was a complex system with multiple components:

Puppeteer crawler executing user-defined scenarios.

Electron application to configure websites crawling.

RabbitMQ message broker for tasks coordination.

C# tasks scheduler and scaped data processor.

Asp.net Angular web app with analogs grid,

prices history and overall system management

Customer has configured scenarios for 500+ websites.

Tasks: on-site search, city/store switch, catalog parse.

Performance: 300K prices per day using 20 instances.

My roles on the project: Team Lead, Architect.