Low-Latency Market Screener & Native Desktop Engine in C++20

What I Built (In Plain English)

Scanning thousands of stocks and options contracts every second requires extreme speed. Most trading tools are built with bloated web wrappers (like Electron) that eat gigabytes of RAM and lag when markets get volatile.

I built a native desktop application powered by a multithreaded C++20 engine under the hood. It connects directly to bank APIs, scans the entire market in real-time, decrypts security tokens locally, and renders an instant desktop dashboard with zero lag.

⚠️ Tech Ahead: The sections below break down the C++20 multithreaded scanning loop, native Cocoa/WebKit window bridging, local Crow WebSocket streaming, and AES-256-GCM token decryption.

System Architecture

                       ┌───────────────────────────────┐
                       │  trader_engine (Main Process) │
                       │                               │
                       │     Native Cocoa/WebKit GUI   │
                       │       (Embedded Window)       │
                       └──────────────┬────────────────┘
                                      │ Displays UI
                                      ▼
           ┌─────────────────────────────────────────────────────┐
           │            Multithreaded C++ Services               │
           │                                                     │
           │  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐  │
           │  │ Crow HTTP/WS │ │  SQLite DB   │ │ Saxo OpenAPI │  │
           │  │  (Port 8080) │ │  (screener)  │ │ (AES Decrypt)│  │
           │  └──────────────┘ └──────────────┘ └──────────────┘  │
           └─────────────────────────────────────────────────────┘

Technical Features

1. Multithreaded Rule Evaluation: Parallel screening loops ingest live equities and options data across global exchanges, classifying market regimes in real-time.
2. Enterprise Cryptography: Direct OpenSSL integration performing AES-256-GCM token decryption for Saxo Bank OpenAPI OAuth2 tokens, guaranteeing local credential security without cloud reliance.
3. Embedded Desktop Integration: Native Cocoa application embedding WebKit, communicating locally with the C++ core over low-latency WebSockets (Crow framework).
4. Local Data Persistence: High-throughput SQLite3 storage engine for caching tick history, screening rules, and candidate alerts.

Tech Stack

• Backend: C++20, CMake 3.20+, OpenSSL 3.0, Crow C++ microframework.
• Frontend Dashboard: Vite, React 19, TypeScript, Tailwind CSS.
• Broker Interface: Saxo Bank OpenAPI (Streaming REST + WebSocket).