Kalshi

Kalshi is a CFTC-regulated prediction market exchange. Orders use traditional limit-order semantics with the server signing each request using your registered RSA private key — no client-side cryptography required.

At a glance


Chain	None (centralized exchange)
Wallet model	None (USD account balance)
Quote token	USD (cents)
Signing	Server-side (RSA-PSS)
Auth	Kalshi API key ID + RSA private key, registered once

Prerequisites

A funded Kalshi account
A Kalshi API key pair — generate at kalshi.com/account/api by uploading the public half of an RSA keypair you generate locally
Your RSA private key in PEM format

If you don’t already have an RSA keypair, generate one:

openssl genrsa -out kalshi-key.pem 2048
openssl rsa -in kalshi-key.pem -pubout -out kalshi-key.pub

Upload kalshi-key.pub to Kalshi. Note the API key ID it returns (a UUID).

One-time setup: register credentials

import { DelphiClient } from '@delphimarkets/sdk';
import { readFileSync } from 'node:fs';

const client = new DelphiClient({
  apiKey: process.env.DELPHI_API_KEY!,
  baseUrl: 'https://api.delphiterminal.co',
});

await client.registerCredentials('kalshi', {
  api_key: process.env.KALSHI_API_KEY_ID!,                       // UUID from Kalshi
  api_secret: readFileSync('./kalshi-key.pem', 'utf-8'),         // RSA PEM, full -----BEGIN... block
  api_passphrase: '',                                             // unused for Kalshi
});

Run this once per user. The Delphi server stores the RSA key encrypted at rest and uses it to sign every Kalshi request you make through the proxy.

Place an order

const order = await client.placeOrder({
  exchange: 'kalshi',
  market_id: 'KXNHLGAME-26MAR30PITNYI-NYI',
  order_type: 'GTC',
  signed_order: {
    ticker: 'KXNHLGAME-26MAR30PITNYI-NYI',
    side: 'yes',           // 'yes' or 'no' — which Kalshi outcome
    action: 'buy',         // 'buy' or 'sell' (default: 'buy')
    type: 'limit',         // always 'limit' (Kalshi only supports limit orders here)
    price_cents: '54',     // limit price in cents, 1-99
    count: '1',            // number of contracts
  },
});

console.log(`Placed: ${order.order_id} (${order.status})`);

Order parameters

Field	Type	Description
`ticker`	`string`	Kalshi market ticker (e.g. `KXNHLGAME-26MAR30PITNYI-NYI`).
`side`	`'yes' \| 'no'`	The outcome you’re trading — Kalshi sides are by outcome, not buy/sell direction.
`action`	`'buy' \| 'sell'`	Default `'buy'`. To exit a position, use `'sell'`.
`type`	`'limit'`	Always `'limit'`.
`price_cents`	`string`	Limit price in cents (1-99). `'54'` = 54¢ = $0.54.
`count`	`string`	Number of contracts.

Kalshi prices are in cents, not dollars or fractions. A 54¢ limit means price_cents: '54', not '0.54'.

Query and cancel

const status = await client.getOrder(order.order_id, 'kalshi');
const all = await client.listOrders('kalshi');
await client.cancelOrder(order.order_id, 'kalshi');

Common pitfalls

401 Unauthorized: 'invalid signature'

The server’s signature is being rejected by Kalshi. Usually one of:

The PEM you registered isn’t the private half of the keypair you uploaded to Kalshi
The PEM has Windows line endings (\r\n) — re-save the file with Unix line endings (\n)
The PEM is missing the -----BEGIN PRIVATE KEY----- / -----END PRIVATE KEY----- envelope

Re-register with a fresh PEM read via readFileSync('./kalshi-key.pem', 'utf-8').

Order rejected: 'invalid market ticker'

Kalshi tickers can change format between events. Pull the latest market list from GET /api/v1/klsi/markets (or the Kalshi API directly) before placing orders to confirm the ticker is current.

Position limit error

Kalshi imposes per-market position limits (often $25,000 max exposure per market for retail accounts). Check your remaining headroom in the Kalshi UI before placing a large order.

Sandbox vs production

Kalshi has separate api.elections.kalshi.com (production) and demo-api.kalshi.co (sandbox) endpoints. The Delphi server uses production by default. Sandbox API keys are not interchangeable. If you want sandbox access for testing, contact Delphi support.

API reference

POST /api/v1/orders — accepts a KalshiLimitOrder in signed_order
POST /api/v1/users/{userID}/credentials — pass _ as the path segment

Trading SDK

Trading API

Credentials

Polymarket Onboarding

At a glance

Prerequisites

One-time setup: register credentials

Place an order

Order parameters

Query and cancel

Common pitfalls

API reference

​At a glance

​Prerequisites

​One-time setup: register credentials

​Place an order

​Order parameters

​Query and cancel

​Common pitfalls

​API reference

At a glance

Prerequisites

One-time setup: register credentials

Place an order

Order parameters

Query and cancel

Common pitfalls

API reference