Kalshi Position Tracker & Trading API

A lightweight FastAPI service and CLI toolkit for interacting with Kalshi’s trading API.
It supports market polling, position tracking, and order execution using Kalshi’s PSS-signed authentication flow.

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Features

• Secure Authentication – Uses RSA-PSS signatures (via private keys) to sign all Kalshi API requests.
• Market Monitoring – Continuously polls market data and open positions every few seconds.
• Trading Endpoints – Provides /api/order/buy, /api/order/sell, and /api/orders/cancel/{id} endpoints for order execution.
• Position Tracking – Computes liquidation value, realized PnL, and exposure per market.
• Environment Isolation – Separate key handling for demo and production environments.
• Docker-Ready – Containerized setup for quick deployment.

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Project Structure

├── api_keys/
│ ├── demo/
│ │ └── private_key.pem
│ └── prod/
│   └── private_key.pem
├── static/
│ └── index.html # Basic frontend or status page
├── kalshi_positions.py # Core API & position logic
├── server.py # FastAPI web server
├── requirements.txt # Python dependencies
├── Dockerfile # Container build definition
├── README.md
└── LICENSE

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Environment Setup

Create a .env file in the project root:

# Select environment: DEMO or PROD
ENV=DEMO

# API credentials
DEMO_KEYID=<your_demo_key_id>
DEMO_KEYFILE=api_keys/demo/private_key.pem

# For production
PROD_KEYID=<your_prod_key_id>
PROD_KEYFILE=api_keys/prod/private_key.pem

# Event ticker to monitor
EVENT_TICKER=KXNFLGAME-25OCT12CLEPIT

Install dependencies:

python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

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Running the Server

python server.py

The API runs by default at http://localhost:8000.

Using Docker

docker build -t kalshi-api .
docker run -p 8000:8000 --env-file .env kalshi-api

Polling Behavior

The server continuously runs two background tasks:

poll_markets() → updates market/position info every 0.5s

poll_resting_orders() → refreshes resting orders every 3s

These tasks maintain a real-time in-memory state that feeds the /api/status endpoint.

Core Logic (kalshi_positions.py)

Authentication:

Uses cryptographic signatures with cryptography to authorize every request.

Fee Model:

Implements Kalshi’s taker fee formula

fee=0.07×P×(1−P)

where P is the contract price in dollars.

Position Computation:

Calculates liquidation value, realized PnL, and net exposure across all active markets.

Example API Call

curl -X POST http://localhost:8000/api/order/buy \
     -H "Content-Type: application/json" \
     -d '{"ticker": "KXNFLGAME-25OCT12CLEPIT", "side": "yes", "quantity": 2}'

Example Response

{
  "order": {
    "ticker": "KXNFLGAME-25OCT12CLEPIT",
    "status": "executed",
    "taker_fill_cost_dollars": "0.42",
    "taker_fees_dollars": "0.01",
    "last_update_time": "2025-11-07T00:15:23.125Z"
  }
}

Developer Notes

• Designed for low-latency polling (≤ 500 ms loop).
• Easily extendable for event streaming or WebSocket output.
• static/index.html can be replaced with a richer UI dashboard.

License

This project is distributed under the MIT License.