📈 Crypto Simulator

Real-time multi-coin trading simulator with WebSocket price feed and QA chaos controls.

Overview

The Crypto Simulator provides a live multi-coin trading environment over WebSocket. Each user starts with a $10,000 USD balance and can buy and sell BTC, ETH, SOL, and DOGE in real time. Prices update every second using a market simulation engine with distinct patterns (bull flag, channel up, random walk).

The built-in QA Control Panel lets testers inject latency, simulate server crashes, send malformed WebSocket payloads, and force price directions — all without touching the server code.

Quick Start

1. Connect to the WebSocket at ws://<host>/ws/crypto with your API key as a query param or in the first message.
2. Receive live price ticks — the server broadcasts prices for all 4 coins every second.
3. Send a BUY or SELL message to trade.
4. Check your portfolio via the REST endpoint GET /api/crypto/profile.

# Get live prices (no auth required)
curl https://qacloud.dev/api/crypto/prices

# Get portfolio (auth required)
curl https://qacloud.dev/api/crypto/profile \
  -H "x-api-key: YOUR_KEY"

# WebSocket trade message (send after connecting)
{
  "action": "BUY",
  "symbol": "BTC",
  "amount": 0.01
}

# Force BTC to trend upward for 15 seconds
curl -X POST "https://qacloud.dev/api/crypto/inject?symbol=BTC&direction=up&duration=15" \
  -H "x-api-key: YOUR_KEY"

Supported Coins

Each coin has a minimum price floor and its own volatility coefficient. The price engine prevents any coin from dropping below its minimum price.

WebSocket Price Feed

Connect to ws://<host>/ws/crypto to receive live price broadcasts. The server emits a tick every second containing current prices for all coins.

Incoming Tick Message (server → client)

{
  "type": "tick",
  "prices": {
    "BTC": 46230.50,
    "ETH": 2847.12,
    "SOL": 182.44,
    "DOGE": 0.1923
  },
  "timestamp": 1715000000000
}

Authentication

Pass your API key as a query parameter when connecting: ws://<host>/ws/crypto?api_key=YOUR_KEY, or send it in the first message. Without a valid key, trades will fail but price ticks will still be received.

Trading via WebSocket

All buy/sell operations are sent as WebSocket messages. The server processes the trade at the current price and responds with the updated state.

Buy Order

{
  "action": "BUY",
  "symbol": "ETH",
  "amount": 0.5
}

Purchases amount units of the coin at the current price. Deducts the USD cost from your balance.

Sell Order

{
  "action": "SELL",
  "symbol": "ETH",
  "amount": 0.5
}

Sells amount units at the current price. Returns USD to your balance.

Trade Response

{
  "type": "trade_result",
  "success": true,
  "action": "BUY",
  "symbol": "ETH",
  "amount": 0.5,
  "price": 2847.12,
  "cost": 1423.56,
  "balance_usd": 8576.44,
  "coin_balance": 0.5
}

QA Control Panel

The Crypto Simulator includes a built-in QA Control Panel accessible from the app UI. It gives testers direct access to chaos scenarios without writing code.

Price Patterns

The price engine cycles through three patterns every 50 ticks (~50 seconds). Each pattern applies a different movement algorithm to produce realistic chart shapes.

When a price injection is active, the normal pattern is overridden with a strong directional delta toward the injected direction.

REST Endpoints

{
  "prices": { "BTC": 46230.50, "ETH": 2847.12, ... },
  "coins": { "BTC": { "name": "Bitcoin", "pair": "BTC/USD", "icon": "₿" }, ... }
}

{
  "balance_usd": 8576.44,
  "portfolio_value": 11423.56,
  "pnl_total": 1423.56,
  "holdings": [
    { "symbol": "BTC", "balance": 0.02, "price": 46230.50, "value": 924.61, "pnl": 24.61 }
  ],
  "orders": [...],
  "total_trades": 7
}

{
  "symbol": "BTC",
  "direction": "up",
  "duration": 15,
  "message": "BTC will trend up for 15s",
  "endsAt": "2026-04-14T10:00:15.000Z"
}

Test Cases

QA Tasks