Kalshi + Polymarket Trading Toolkit

TypeScript app for Bitcoin 15-minute up/down markets on Kalshi and Polymarket: Kalshi REST API, Polymarket CLOB/Gamma, dual-venue monitoring, and cross-venue arbitrage.

About Developer

Here is Alexei who is expert of trading bot development especially EVM, Solana and Prediction market such as Polymarket, Klashi, etc. If you have any question for dev, contact me via telegram(https://t.me/@bitship1_1)

Prove of Work

Please check this log to see how the bot is working here

Features

• Balance — Kalshi portfolio balance (REST).
• Kalshi single order — One limit order on the first open KXBTC15M market.
• Dual-venue monitor — Best-ask prices from Kalshi + Polymarket; 15m-slot logs; optional process restart at :00/:15/:30/:45; integrated arb.
• Cross-venue arb — When sum of opposite sides is in [ARB_SUM_LOW, ARB_SUM_THRESHOLD), place one order on each venue (at most one per leg per market).
• Polymarket single order — One limit buy for the DOWN token on the current BTC 15m market.

Setup

cp .env.sample .env
# Set KALSHI_API_KEY and KALSHI_PRIVATE_KEY_PATH or KALSHI_PRIVATE_KEY_PEM
npm install

For Polymarket orders / arb Poly leg: set POLYMARKET_PRIVATE_KEY and POLYMARKET_PROXY. The monitor uses polymarket-validator for config validation at startup.

Scripts

Command	Description
npm start	Run dual price monitor + arb (single-instance lock, 15m log files).
npm run balance	Fetch and print Kalshi portfolio balance.
npm run kalshi-single-order	Place one Kalshi limit order on first open KXBTC15M market.
npm run poly-single-order	Place one Polymarket limit buy (DOWN token). Optional: [price] [size].
npm run build	Compile TypeScript to dist/.

Environment

Kalshi (required): KALSHI_API_KEY, KALSHI_PRIVATE_KEY_PATH or KALSHI_PRIVATE_KEY_PEM. Optional: KALSHI_DEMO, KALSHI_BASE_PATH.

Bot: KALSHI_BOT_SIDE (yes/no), KALSHI_BOT_PRICE_CENTS, KALSHI_BOT_CONTRACTS, KALSHI_BOT_MAX_MARKETS, KALSHI_BOT_DRY_RUN.

Monitor: KALSHI_MONITOR_INTERVAL_MS (default 200), KALSHI_MONITOR_TICKER (optional), KALSHI_MONITOR_NO_RESTART (disable 15m restart).

Arb: ARB_SUM_THRESHOLD (default 0.92), ARB_SUM_LOW (default 0.75), ARB_PRICE_BUFFER, ARB_SIZE, ARB_DRY_RUN.

Polymarket: POLYMARKET_PRIVATE_KEY, POLYMARKET_PROXY; optional: POLYMARKET_CLOB_URL, POLYMARKET_CHAIN_ID, POLYMARKET_TICK_SIZE, POLYMARKET_NEG_RISK, POLYMARKET_CREDENTIAL_PATH, POLYMARKET_MIN_USD.

See .env.sample for all variables.

Monitor & arb

npm start starts the dual monitor. It polls at KALSHI_MONITOR_INTERVAL_MS, logs to console and logs/monitor_YYYY-MM-DD_HH-{00|15|30|45}.log, and runs arb when the combined price (e.g. Kalshi UP + Polymarket DOWN) is in range. One monitor process only (logs/monitor.lock). Without KALSHI_MONITOR_TICKER, the process can restart at quarter-hour boundaries; set KALSHI_MONITOR_NO_RESTART=true to disable.

Examples

# Dry run Kalshi order
KALSHI_BOT_DRY_RUN=true npm run kalshi-single-order

# Kalshi YES @ 50¢, 2 contracts
KALSHI_BOT_SIDE=yes KALSHI_BOT_PRICE_CENTS=50 KALSHI_BOT_CONTRACTS=2 npm run kalshi-single-order

# Polymarket DOWN @ 0.45, size 10
npm run poly-single-order 0.45 10

Programmatic API

• Kalshi: placeOrder(ticker, side, count, priceCents, options?) from ./bot or ./orders.
• Polymarket: placePolymarketOrder(tokenId, price, size, options?) from ./polymarket-order or ./orders. Token IDs: getTokenIdsForSlugCached(slug) in ./polymarket-monitor.

Stack

Node/TypeScript, kalshi-typescript, @polymarket/clob-client, ethers, polymarket-validator.

Docs

Kalshi API · TypeScript SDK · WebSockets