Why I rebuilt India Post tracking in Rust and WebAssembly

• Used Rust compiled to WASM for the frontend to eliminate client runtime exceptions and process large CSV tables directly in-browser with zero VDOM lag.
• Used FastAPI with asyncio.gather() and HTTPX connection pooling to fan out 200 requests concurrently without blocking the server thread.
• Containerized stack with Docker Compose and Nginx, where Nginx serves static WASM MIME types and reverse-proxies `/api` to Uvicorn.

import asyncio
import httpx

async def track_single(client: httpx.AsyncClient, tracking_id: str) -> dict:
    try:
        response = await client.get(f"/upstream/track/{tracking_id}", timeout=8.0)
        return parse_tracking_payload(response.text)
    except Exception as exc:
        return {"id": tracking_id, "status": "RETRY_REQUIRED", "error": str(exc)}

async def track_batch(tracking_ids: list[str]) -> list[dict]:
    # Connection pooling with strict limits to prevent socket exhaustion
    limits = httpx.Limits(max_keepalive_connections=20, max_connections=50)
    async with httpx.AsyncClient(limits=limits) as client:
        tasks = [track_single(client, tid) for tid in tracking_ids]
        return await asyncio.gather(*tasks)