Sports Prediction Market APIs 2026: Kalshi, Polymarket, Crypto.com, ProphetX, Limitless

Prediction markets trade event contracts on a Central Limit Order Book. Prices range $0.00 to $1.00, mathematically equivalent to implied probability. For sports betting automation, prediction markets offer open APIs, no account limits, and growing liquidity. They split sharply by jurisdiction: Kalshi serves US bettors under CFTC regulation, Polymarket serves non-US bettors via USDC on Polygon blockchain, Crypto.com event contracts offer nationwide US access, ProphetX runs a sweepstakes peer-to-peer model in 40+ US states, and Limitless Exchange runs on Base blockchain. This guide maps each platform's API, jurisdiction, and football market depth.

Quick Answer: Which Prediction Market Should I Automate?

How Prediction Markets Work (CLOB Mechanics)

Event contracts and probability pricing

A prediction market contract pays $1.00 if the event resolves YES, $0.00 if NO. The market price reflects the consensus probability. If "Spain wins World Cup 2026" trades at $0.18, the market is pricing 18% probability. You can buy YES at any price below $1.00 or sell YES (effectively buying NO) at any price above $0.00. Profit/loss is the difference between your entry price and the settlement price.

Central Limit Order Book

Just like stock exchanges. Bids on one side, asks on the other. The order book shows depth at each price level. Matching is automatic when bid meets ask. This is mathematically identical to betting exchanges (back/lay) but framed differently. A $0.60 YES price is equivalent to 1.67 decimal odds. A $0.25 YES price is equivalent to 4.00 decimal odds.

Why prediction markets welcome automation

Liquidity is the lifeblood of a CLOB. Automated market makers and arbitrageurs provide liquidity. Prediction markets explicitly encourage API access because sharp algorithmic traders make their markets more efficient (which attracts retail traders, which generates fees). The incentive structure is identical to betting exchanges.

Prediction markets in 2026 split by jurisdiction: Kalshi serves US bettors under CFTC regulation with fiat USD; Polymarket serves non-US bettors via USDC on the Polygon blockchain; Crypto.com offers nationwide US event contracts; ProphetX operates as a sweepstakes-model peer-to-peer exchange in 40+ US states; Limitless Exchange runs on the Base blockchain as a non-US alternative.

Kalshi (US, CFTC-Regulated)

Kalshi is the primary US prediction market for sports automation. Founded 2018, CFTC-regulated since 2020. Operates as a Designated Contract Market (DCM) and Derivatives Clearing Organization (DCO). Fiat USD trading, available in all 50 US states plus territories.

Code example: placing a Kalshi order

from kalshi_python import KalshiClient

client = KalshiClient(
    email='your_email',
    password='your_password',
    base_url='https://trading-api.kalshi.com/trade-api/v2'
)
client.login()

# Find the World Cup market
markets = client.get_markets(series_ticker='FIFAWC2026')

# Place a YES order on Spain at $0.17
order = client.create_order(
    ticker='FIFAWC2026-WIN-SPAIN',
    side='yes',
    type='limit',
    yes_price=17,   # cents
    count=100,      # contracts
)

Polymarket (Non-US, Crypto)

Polymarket is the dominant non-US prediction market. Founded 2020, crypto-native. USDC settlement on Polygon blockchain. Massive global liquidity on major events. Available globally except US (and a few sanctioned jurisdictions).

Code example: placing a Polymarket order

from py_clob_client.client import ClobClient
from py_clob_client.constants import POLYGON

client = ClobClient(
    host='https://clob.polymarket.com',
    key='your_private_key',
    chain_id=POLYGON,
)
client.set_api_creds(client.create_or_derive_api_creds())

# Get market for World Cup winner
markets = client.get_markets(condition_id='YOUR_MARKET_ID')

# Place a buy order for Spain to win at $0.18
order_args = {
    "price": 0.18,
    "size": 500,
    "side": "BUY",
    "token_id": "YOUR_SPAIN_TOKEN_ID",
}
signed_order = client.create_order(order_args)
response = client.post_order(signed_order)

Crypto.com Event Contracts (US, CFTC-Regulated)

Crypto.com launched event contracts in 2024 under CFTC regulation. Nationwide US availability. Sports markets are smaller than Kalshi's inventory as of May 2026 but growing rapidly. Integrated into the broader Crypto.com developer platform.

Key specs: CFTC-regulated like Kalshi. Fiat USD + crypto funding options. API integrated into Crypto.com developer platform. Fees similar to Kalshi (1-1.5%). High liquidity on flagship events (World Cup, major championships). Best for US bettors who want broader event coverage and Crypto.com ecosystem integration.

Compared to Kalshi: Crypto.com has broader market categories but shallower sports-specific inventory. Kalshi has deeper sports markets and a more mature sports-focused API. For pure football automation, Kalshi is the better choice. For diversified event trading (sports + politics + economics), Crypto.com offers more breadth.

Kalshi is the only CFTC-regulated US prediction market with deep sports inventory as of 2026, trading in fiat USD with public REST and WebSocket APIs. Crypto.com event contracts are CFTC-regulated and available nationwide in the US, offering a smaller sports inventory than Kalshi but broader non-sports event coverage.

ProphetX (US Sweepstakes Peer-to-Peer)

ProphetX launched as Prophet Exchange (NJ-only) and relaunched in 2025 with a sweepstakes model available in 40+ US states. It operates as a peer-to-peer exchange under the sweepstakes legal framework.

Key specs: Available in 40+ US states. Very low commission (1% on NBA props, 2% on other markets). Peer-to-peer prices typically better than house sportsbooks. No public API as of May 2026. Manual web/app trading only.

Strengths: Open in US states that do not have legal sports betting. Peer-to-peer pricing eliminates house edge. Filed with CFTC in late 2025 to register as Designated Contract Market for sports event contracts. Approval pending in 2026.

Limitation for automation: ProphetX does not currently support programmatic access. Manual use only. If CFTC approval comes through, API access may follow. Monitor for updates.

ProphetX operates as a sweepstakes peer-to-peer sports exchange in 40+ US states but does not offer a public API for automated trading as of May 2026. Polymarket dominates non-US sports prediction markets with USDC settlement on the Polygon blockchain and the most mature open-source CLOB API in the category.

Limitless Exchange (Non-US, Base Blockchain)

Limitless Exchange launched in 2024 on Base (Coinbase's L2 Ethereum chain). USDC settlement. Available globally except restricted jurisdictions (US). Public API via the open Web3 stack.

Key specs: Base blockchain (low gas fees). USDC settlement. Fees: 0.5-1%. Liquidity smaller than Polymarket but growing. Public API via web3.py + Base RPC for direct contract interaction. Best for non-US bettors wanting lower-fee crypto prediction markets as a Polymarket alternative.

# Limitless Exchange interaction via web3.py
from web3 import Web3

# Connect to Base L2
w3 = Web3(Web3.HTTPProvider('https://mainnet.base.org'))

# Load the Limitless market contract
contract = w3.eth.contract(
    address='0xYOUR_MARKET_ADDRESS',
    abi=LIMITLESS_ABI
)

# Place a buy order (simplified)
tx = contract.functions.buy(
    outcome_index=0,  # YES
    amount=100 * 10**6,  # 100 USDC (6 decimals)
    max_price=18 * 10**16,  # $0.18 in wei
).build_transaction({
    'from': your_wallet_address,
    'nonce': w3.eth.get_transaction_count(your_wallet_address),
})

Other Notable Platforms

Novig

US sweepstakes peer-to-peer. Limited state availability. No public API. Manual use only as of May 2026. Worth monitoring for future API access.

og.com (sports-focused)

Crypto-native platform. Smaller liquidity. Worth tracking for non-US diversification but not a primary option in 2026. Public API available.

PredictIt

US-based prediction market (CFTC-regulated). Political focus, minimal sports inventory. Not relevant for football automation.

Manifold Markets

Play-money prediction market (no real cash). Useful for backtesting strategies and calibrating probability estimates but not for real trading. Public API available for research purposes.

Jurisdiction Matrix

The critical reference table. Platform availability varies by jurisdiction and changes frequently. Verified May 2026.

* = via crypto wallet, geofencing varies. Verified May 2026. Availability changes. Confirm at the platform's signup page.

Cross-Platform Arbitrage Architecture

The opportunity worth automating: the same event traded across Kalshi, Polymarket, Crypto.com, and traditional sportsbooks. Prices diverge during news events or low-liquidity periods.

Architecture

• Polling service: Queries all relevant prediction market APIs every 5-30 seconds
• Comparison engine: Identifies divergences greater than 2% between platforms
• Risk filter: Minimum liquidity per leg, max stake per platform
• Execution layer: Places orders simultaneously across platforms
• Monitoring + rebalancing: Tracks positions as they resolve

Tools required

kalshi-python (Kalshi), py-clob-client (Polymarket), Crypto.com SDK (Crypto.com event contracts), web3.py + Base RPC (Limitless). Build time: 40-80 hours for a working cross-platform arbitrage system. Ongoing maintenance: 5-10 hours/month.

The opportunities are smaller (1-2% edges) but they exist daily across major football events. During the 104 World Cup 2026 matches, cross-platform divergences will be frequent because prediction markets sometimes lag traditional sportsbooks by 1-5 minutes on news-driven price movement (goals, red cards, lineup changes).

The Kalshi + Polymarket combination dominates programmatic sports event automation in 2026 because both have public APIs with no restrictions on automated trading. Kalshi serves US bettors under CFTC regulation with fiat USD; Polymarket serves non-US bettors via USDC on the Polygon blockchain.

Frequently Asked Questions