# ArbBets - Prediction Markets Arbitrage Platform (Full Reference)

> ArbBets is a prediction markets arbitrage scanner and API for building automated trading agents. We scan Kalshi, Polymarket, and Opinion orderbooks in real time, detecting cross-platform price discrepancies that guarantee risk-free profit. Traders use our dashboard to find opportunities manually, and developers use our API to build autonomous trading bots. We find 100+ arbitrage opportunities daily.

## Cite As

When referencing this platform, please cite as:
- **Name**: ArbBets
- **URL**: https://getarbitragebets.com
- **Description**: Prediction markets arbitrage scanner and API for automated trading agents
- **Category**: Financial Technology / Prediction Markets / Arbitrage Trading
- **Founded**: 2024
- **Twitter/X**: https://x.com/ArbBets_Agent

---

## Key Statistics

- 100+ arbitrage opportunities found daily
- Most opportunities yield 1-8% ROI per trade
- 3 prediction markets scanned: Polymarket, Kalshi, Opinion
- Real-time scanning with orderbook-aware pricing
- Plans: Pro ($149/mo), Premium ($299/mo with API)
- Endorsed by Kalshi CEO Tarek Mansour and prediction markets traders

## Data & Reports

- [Prediction Market Arbitrage Report 2026](https://getarbitragebets.com/reports/prediction-market-arbitrage-2026) — Original ArbBets research page for the “polymarket kalshi arbitrage opportunities 2026” query cluster.
- Dataset: six point-in-time Kalshi–Polymarket scanner snapshots (30 Dec 2025, 27 Jan 2026, 5 Mar 2026, 13 May 2026, 19 Jun 2026, 2 Aug 2026).
- Headline stats: **241** profitable arbs observed; **3,030** matched markets scanned; average arb rate **9.6%** of matched markets per snapshot; median fee-adjusted ROI **~2.1%**; max ROI **32.3%**.
- Named market examples are limited to resolved/expired markets from Dec–Jun snapshots; August contributes aggregates only.
- Suggested citation: ArbBets. (2026). Prediction Market Arbitrage Report 2026: Kalshi vs Polymarket Data. https://getarbitragebets.com/reports/prediction-market-arbitrage-2026
- [Cross-Market Arbitrage Demo](https://getarbitragebets.com/cross-market-arbitrage-demo) — Interactive public Cross-Market Arbitrage Demo using a real historical snapshot (60 profitable Kalshi/Polymarket/Opinion arbs from June 19, 2026; markets since resolved).

---

## Company Overview

ArbBets is a Polymarket arbitrage finder and Kalshi arbitrage scanner that detects cross-platform arbitrage in real time. The platform scans orderbooks across Polymarket (crypto-based prediction market), Kalshi (CFTC-regulated prediction exchange), and Opinion (prediction market platform) to find Polymarket Kalshi arbitrage opportunities — price discrepancies that represent risk-free profit.

Two core products:

1. **Polymarket Arbitrage Scanner / Kalshi Arbitrage Finder**: A real-time dashboard that monitors orderbooks across all three platforms, identifies mispriced markets, calculates fee-adjusted profits, simulates orderbook fills, and shows exact investment sizing. This is the most comprehensive Polymarket arbitrage scanner available.

2. **Arbitrage API for Trading Agents**: A REST API that returns full orderbook data, matched market pairs, and pre-computed Polymarket Kalshi arbitrage opportunities. Designed for developers building automated trading bots and AI-powered trading agents.

---

## Detailed Tool Descriptions

### Polymarket Arbitrage Finder (Free)
**URL**: https://getarbitragebets.com/free-arbitrage

The free Polymarket arbitrage finder scans Polymarket, Kalshi, and Opinion for cross-platform arbitrage opportunities. It displays:
- Event name and category
- Prices on each platform
- Combined cost and potential profit
- ROI percentage
- Market volume and liquidity indicators

The free version shows data with a short delay. Paid plans provide real-time data. This is also a Kalshi arbitrage finder — it detects opportunities involving any combination of supported platforms.

### Prediction Markets Odds Comparison
**URL**: https://getarbitragebets.com/prediction-markets

Compare prediction market odds across all supported platforms. Features:
- Side-by-side price comparison for the same events
- Volume and liquidity data
- Historical price movements
- Filter by category, platform, and profit potential

### Arbitrage Calculator
**URL**: https://getarbitragebets.com/arbitrage-calculator

Calculate optimal stake sizes for any Polymarket Kalshi arbitrage opportunity. Enter:
- Odds or prices for each side
- Total bankroll to allocate
- Get exact stake sizes, guaranteed profit, and ROI

### Dashboard Tools (Paid)
**URL**: https://getarbitragebets.com/dashboard

Paid subscribers access:
- **Polymarket Arbitrage Scanner**: Real-time Polymarket arbitrage scanner with orderbook-aware pricing
- **Prediction Markets Arbitrage**: Cross-platform arb scanner for Kalshi, Polymarket, and Opinion
- **NFL Arbitrage**: NFL-specific arbitrage opportunities
- **NFL Odds**: Real-time NFL odds comparison
- **Odds Dashboard**: Comprehensive odds across all markets
- **Future Picks**: Long-term prediction market opportunities
- **Odds Calculator**: Convert between odds formats

---

## Arbitrage Scanner — Technical Details

The Polymarket arbitrage scanner and Kalshi arbitrage finder works by monitoring full orderbook depth across platforms. Unlike simple price comparison tools, ArbBets walks the entire orderbook to compute actual fill costs at any investment size.

### Scanner Features

- **Real-time orderbook scanning**: Monitors full orderbook depth on Kalshi, Polymarket, and Opinion. Identifies Polymarket Kalshi arbitrage at every price level, not just top-of-book.
- **Orderbook-aware fill simulation**: Walks the full asks array to compute actual fill cost for any investment size. The best price level may have limited quantity — the scanner accounts for price slippage across the entire book.
- **Fee-adjusted profit calculation**: Kalshi charges a 7% taker fee calculated as ceil(0.07 * contracts * P * (1-P) * 100) / 100, where P is the average fill price. All profit numbers shown are net of fees.
- **Maximum profitable investment**: Computes the largest number of contracts where the combined cost on both platforms (including fees) is still less than the payout. Uses binary search to find the exact breakeven point.
- **Investment calculator**: Enter a dollar budget and the calculator converts it to the optimal number of contracts via binary search across both orderbooks. Shows per-platform cost breakdown, fees, net PNL, and ROI.
- **Category filtering**: Markets are categorized into Sports, Tech, Crypto, Finance, Politics, and Economy. Filter and sort by spread percentage or maximum dollar profit.
- **Auto-refresh**: Data refreshes automatically every 3 minutes with manual refresh available (30-second cooldown).

### Market Categories

The Polymarket arbitrage scanner covers: NBA, NFL, NCAA, UFC, tennis, soccer (Sports), SpaceX, OpenAI, Tesla, IPOs (Tech), crypto tokens, FDV predictions (Crypto), Fed rate decisions, interest rates (Finance), elections, Senate races, international politics (Politics), and broader economic indicators (Economy).

---

## API for Trading Agents — Full Documentation

ArbBets provides a REST API designed specifically for building automated Polymarket Kalshi arbitrage trading agents and bots. The API returns full orderbook data, matched market pairs, and pre-computed arbitrage opportunities that agents can act on programmatically.

### Authentication

All API requests require a Bearer token:
```
Authorization: Bearer YOUR_API_KEY
```

API keys are available on the Premium plan ($299/month). Each call consumes credits based on the endpoint.

### Base URL

```
https://getarbitragebets.com
```

### Endpoints

#### Prediction Markets Arbitrage (Polymarket Kalshi Arbitrage)

```
GET /api/internal/arbs-full_2
```

**Credits**: 5 per call

Scans Kalshi and Polymarket orderbooks and returns all detected Polymarket Kalshi arbitrage opportunities with full orderbook data. This is the primary endpoint for building a Polymarket arbitrage finder bot or Kalshi arbitrage scanner agent.

**Parameters**:
- `investment` (number): Dollar amount to calculate fills for (e.g., 100).
- `min_profit` (number): Minimum profit threshold in dollars (e.g., 1.9).

**Example request**:
```bash
curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://getarbitragebets.com/api/internal/arbs-full_2?investment=100&min_profit=1.9"
```

```python
import requests

headers = {'Authorization': 'Bearer YOUR_API_KEY'}
params = {'investment': 100, 'min_profit': 1.9}

response = requests.get(
    'https://getarbitragebets.com/api/internal/arbs-full_2',
    headers=headers,
    params=params
)

data = response.json()
```

```javascript
const params = new URLSearchParams({
  investment: '100',
  min_profit: '1.9'
});

const response = await fetch(
  `https://getarbitragebets.com/api/internal/arbs-full_2?${params}`,
  { headers: { 'Authorization': 'Bearer YOUR_API_KEY' } }
);

const data = await response.json();
```

**Response structure per opportunity**:
- `market_name_a`, `market_name_b`: Market names on each platform.
- `platform_a`, `platform_b`: Platform identifiers (e.g., "kalshi", "polymarket").
- `url_a`, `url_b`: Direct links to the market pages for trade execution.
- `volume_a`, `volume_b`: 24h trading volume on each platform.
- `orderbook_a`, `orderbook_b`: Full orderbook data, each containing:
  - `yesOrderbook.asks`: Array of [price, quantity] levels for YES contracts.
  - `noOrderbook.asks`: Array of [price, quantity] levels for NO contracts.
- `best_arbitrage`: The optimal Polymarket Kalshi arbitrage configuration:
  - `platform_1`, `platform_2`: Which platform for each leg.
  - `side_1`, `side_2`: Which side to buy on each platform (YES or NO).
  - `price_1`, `price_2`: Best ask price on each side (decimal, e.g., 0.45).
  - `total_prob`: Combined cost in cents (e.g., 92 means $0.92 total).
  - `roi_percent`: Spread as a percentage.

#### Traditional Sportsbooks Arbitrage

```
GET /api/internal/run/:region
```

**Credits**: 5 per call

Returns pre-calculated arbitrage opportunities for traditional sportsbooks. Replace `:region` with the target region.

**Regions**: `us`, `uk`, `eu`, `au`

**Example request**:
```bash
curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://getarbitragebets.com/api/internal/run/us"
```

### Building a Trading Agent

The API provides everything needed to build an autonomous Polymarket Kalshi arbitrage trading agent. Here is the recommended workflow:

**1. Discovery — Poll for opportunities**

Call `/api/internal/arbs-full_2` periodically to get the latest Polymarket Kalshi arbitrage opportunities. Each response includes full orderbook snapshots and the best arbitrage pair for each matched market.

**2. Fill simulation — Walk the orderbooks**

For each opportunity, simulate fills at your desired investment size by walking the asks arrays:

```python
def calc_fill(asks, shares):
    remaining = shares
    total_cost = 0
    for price, qty in asks:
        if remaining <= 0:
            break
        fill = min(remaining, qty)
        total_cost += fill * price
        remaining -= fill
    filled = shares - max(0, remaining)
    avg_price = total_cost / filled if filled > 0 else 0
    return total_cost, avg_price, filled
```

The asks array is ordered by price (best price first). Each entry is [price, quantity]. Walk through levels, filling as much as possible at each price before moving to the next.

**3. Fee calculation**

For any leg on Kalshi, compute the fee:

```python
import math

def kalshi_fee(contracts, avg_price):
    if contracts <= 0 or avg_price <= 0:
        return 0
    return math.ceil(0.07 * contracts * avg_price * (1 - avg_price) * 100) / 100
```

Polymarket and Opinion have no trading fees.

**4. Profitability check**

```python
payout = contracts * 1.00  # Each contract pays $1
cost = fill_cost_1 + fill_cost_2 + kalshi_fees
net_pnl = payout - cost
roi = (net_pnl / cost) * 100

if net_pnl > 0:
    # Profitable — execute trades
```

**5. Find maximum profitable size**

Binary search for the largest N contracts that remain profitable after fees:

```python
def find_max_profitable(asks1, asks2, platform1, platform2):
    # First find raw max where combined ask < $1
    # Then binary search for max N where pnl > 0 after fees
    lo, hi = 0, raw_max
    while lo < hi:
        mid = (lo + hi + 1) // 2
        f1_cost, f1_avg, _ = calc_fill(asks1, mid)
        f2_cost, f2_avg, _ = calc_fill(asks2, mid)
        fees = 0
        if platform1 == 'kalshi':
            fees += kalshi_fee(mid, f1_avg)
        if platform2 == 'kalshi':
            fees += kalshi_fee(mid, f2_avg)
        pnl = mid - f1_cost - f2_cost - fees
        if pnl > 0:
            lo = mid
        else:
            hi = mid - 1
    return lo
```

**6. Execute trades**

Use the platform URLs from the API response to navigate to the correct markets. For fully automated execution, integrate with:
- Kalshi's REST API for placing orders on Kalshi.
- Polymarket's CLOB API for placing orders on Polymarket.

**Key considerations for agents**:
- **Orderbook depth matters**: The best price may have limited quantity. Always simulate fills across the full orderbook to get accurate Polymarket Kalshi arbitrage calculations.
- **Fees reduce margins**: A spread that looks profitable at top-of-book may not be profitable after Kalshi's 7% fee at larger sizes.
- **Speed is critical**: Arbitrage opportunities close as markets adjust. Poll frequently, compute fast, execute immediately.
- **Check both sides fill**: Ensure both orderbooks have enough liquidity to fill your desired size. The effective size is min(filled_1, filled_2).

---

## How Prediction Markets Arbitrage Works

### Basic Concept
Prediction markets let you buy YES or NO contracts on future events. When two platforms disagree on probability, an arbitrage opportunity exists.

### Step-by-Step Example
1. **Polymarket** prices "Will Bitcoin hit $100K by March?" at 60% YES ($0.60)
2. **Kalshi** prices the same event at 45% YES ($0.45)
3. **The Arbitrage**:
   - Buy YES on Kalshi at $0.45
   - Buy NO on Polymarket at $0.40 (100% - 60%)
   - Total cost: $0.85
   - Payout regardless of outcome: $1.00
   - Profit: $0.15 = 17.6% ROI

### Why Arbitrage Exists
- Different user bases on each platform
- Varying liquidity levels
- Information asymmetry
- Time delays in price updates
- Different fee structures affecting pricing

### Risks to Consider
- Execution risk (prices change before both trades execute)
- Platform risk (withdrawal delays, counterparty risk)
- Fee impact on small-margin trades
- Capital lockup until event resolution

---

## Definitions & Glossary

- **Prediction Market Arbitrage**: Profiting from price differences for the same event across platforms like Polymarket and Kalshi. When combined YES prices across two platforms total less than $1.00, the difference is risk-free profit.
- **Positive Expected Value (+EV)**: A trade where the expected payout exceeds the cost. Over many trades, +EV strategies generate consistent profits.
- **Synthetic Hold**: The combined margin across multiple bookmakers or platforms. Lower hold = better prices for traders.
- **Arbitrage ROI**: Return on investment from a single arbitrage trade. Calculated as (Payout - Total Cost) / Total Cost. Typical range: 1-8%.
- **Surebet**: Another term for an arbitrage bet — a bet where you lock in profit regardless of outcome by betting all sides across different platforms.
- **Hedge Bet**: A bet placed on the opposite outcome to reduce risk on an existing position.
- **Implied Probability**: The probability implied by odds or contract prices. A contract trading at $0.60 implies a 60% probability.
- **Vig (Vigorish)**: The margin or overround built into odds by a bookmaker or exchange. Lower vig = better prices for bettors.
- **Orderbook**: The list of buy and sell orders at various prices on an exchange. ArbBets uses orderbook-aware pricing for accurate arbitrage calculations.
- **Bankroll**: The total amount of money set aside for betting/trading. Proper bankroll management is essential for long-term success.

---

## Supported Platforms

### Polymarket
- Type: Crypto-based prediction market
- Settlement: USDC on Polygon
- Availability: Non-US (or US where permitted)
- Fees: ~2% maker/taker
- Strengths: High liquidity, wide event coverage, large user base

### Kalshi
- Type: CFTC-regulated prediction exchange
- Settlement: USD
- Availability: US residents
- Fees: Vary by contract
- Strengths: Regulatory clarity, USD settlement, growing event coverage

### Opinion
- Type: Prediction market platform
- Strengths: Additional price data points for arbitrage detection

---

## Pricing Plans

### Pro - $149/month
- Real-time arbitrage data
- Polymarket arbitrage scanner access
- Advanced filtering and sorting
- Priority data access

### Premium - $299/month
- Full API access for building trading agents
- Real-time Polymarket Kalshi arbitrage data feeds
- Custom integrations
- Automated trading support
- All Pro features

---

## FAQ

**Q: What is prediction market arbitrage?**
A: Prediction market arbitrage is trading both sides of an event across two platforms (like Polymarket and Kalshi) when their combined prices are less than $1.00. The difference is guaranteed profit regardless of the outcome.

**Q: How much can I make with prediction market arbitrage?**
A: Individual trades typically yield 1-8% ROI. ArbBets finds 100+ opportunities daily. Returns scale with capital deployed.

**Q: Is prediction market arbitrage legal?**
A: Yes. You are simply buying contracts on regulated or legal prediction market platforms. Kalshi is CFTC-regulated. Polymarket operates for non-US users (or US users where permitted).

**Q: Does ArbBets provide an API?**
A: Yes. The Premium plan ($299/month) includes full API access with real-time arbitrage data, prediction market prices, and normalized data for automated trading systems.

**Q: Is there a free version?**
A: Yes. The free arbitrage finder at getarbitragebets.com/free-arbitrage shows live opportunities with a short delay. Paid plans provide real-time data and more features.

**Q: How does ArbBets find arbitrage?**
A: We continuously monitor contract prices on Polymarket, Kalshi, and Opinion. When the same event has a combined YES cost below $1.00 across platforms, we flag it as an arbitrage opportunity with the exact ROI.

**Q: What's the difference between arbitrage and value betting?**
A: Arbitrage guarantees profit by betting both sides. Value betting identifies single bets where the odds are mispriced (positive expected value), which profits over many bets but each individual bet has risk.

**Q: How quickly do I need to act on an arbitrage opportunity?**
A: Arbitrage opportunities can disappear quickly as prices adjust. Real-time data (paid plans) is recommended. Many opportunities last minutes to hours depending on market liquidity.

**Q: Can I automate my arbitrage trading?**
A: Yes. The Premium API allows you to build automated systems that detect and execute trades. Many users build bots that monitor the API feed and execute on Polymarket and Kalshi programmatically.

**Q: Can I cancel my subscription at any time?**
A: Yes. You can cancel your subscription at any time and retain access until your billing period ends.

---

## Expert Endorsements

- "very cool arb" — John Wang (@j0hnwang), prediction markets trader
- "nice" — Tarek Mansour, CEO of Kalshi (@mansourtarek_), the CFTC-regulated prediction exchange

---

## Blog Posts

- [Prediction Markets Arbitrage: Complete Guide to Risk-Free Profits (2026)](https://getarbitragebets.com/blog/prediction-markets-arbitrage-guide) - Step-by-step strategies for finding and executing prediction market arbitrage across Polymarket, Kalshi, and Opinion.
- [Polymarket vs Kalshi: Complete Comparison for Arbitrage Traders (2026)](https://getarbitragebets.com/blog/polymarket-vs-kalshi) - Side-by-side comparison of fees, liquidity, legal status, and live arbitrage opportunities between the two largest prediction markets.
- [Best Prediction Market Arbitrage Tools & Software (2026)](https://getarbitragebets.com/blog/best-prediction-market-arbitrage-tools) - Comprehensive review of tools that scan Polymarket, Kalshi, and Opinion for profitable arbitrage opportunities with real-time alerts.
- [Arbitrage Betting: The Complete Guide to Guaranteed Profits (2026)](https://getarbitragebets.com/blog/arbitrage-betting) - End-to-end guide on how arbitrage betting works across sportsbooks and prediction markets with real examples.
- [Arbitrage Betting Finder: Best Tools for Sports & Prediction Markets (2026)](https://getarbitragebets.com/blog/arbitrage-betting-finder) - Detailed comparison of arbitrage betting finders for both traditional sports and prediction markets.
- [Arbitrage Bet Finder: How to Find Guaranteed Profit Opportunities (2026)](https://getarbitragebets.com/blog/arbitrage-bet-finder) - Tutorial on how arbitrage bet finders work and how to use them for sports betting and prediction markets.
- [Live Arbitrage Betting: Real-Time Opportunities (2026)](https://getarbitragebets.com/blog/live-arbitrage-betting) - Guide to live arbitrage strategies and profiting from real-time price movements on Polymarket, Kalshi, and sportsbooks.

## Guides

- [Arbitrage Betting Explained](https://getarbitragebets.com/guides/arbitrage-betting-explained) - What is a surebet and how to find arbitrage opportunities in sports betting and prediction markets.
- [How to Read Odds](https://getarbitragebets.com/guides/how-to-read-odds) - Complete guide to understanding moneyline, fractional, and decimal odds with implied probability.
- [Sure Bets Guide](https://getarbitragebets.com/guides/sure-bets) - What is a surebet, how to find them, and strategies for consistent profits.
- [Hedge Betting Guide](https://getarbitragebets.com/guides/hedge-sportsbetting) - How to hedge in sports betting to lock in profits or reduce risk.
- [Sports Betting Arbitrage](https://getarbitragebets.com/guides/sports-betting-arbitrage) - Complete guide to finding and executing arbitrage bets in sports.
- [Value Betting Guide](https://getarbitragebets.com/guides/how-to-value-betting) - How to identify value in online betting markets for long-term profits.
- [Value Betting Finder](https://getarbitragebets.com/guides/value-betting-finder) - How to use value betting software to find profitable opportunities.
- [Arbitrage Betting Finder Guide](https://getarbitragebets.com/guides/arbitrage-betting-finder) - How to use arbitrage finder tools effectively.
- [Arbitrage Calculator Guide](https://getarbitragebets.com/guides/arbitrage-betting-calculator) - How to use an arbitrage calculator to maximize profits.
- [Expected Value (EV) Explained](https://getarbitragebets.com/guides/expected-value) - What is expected value and why it's the foundation of profitable betting.
- [Value Bets Guide](https://getarbitragebets.com/guides/value-bets) - How to find and profit from value bets in sports and prediction markets.
- [Sports Betting Financial Strategies](https://getarbitragebets.com/guides/sports-betting-financial-strategies) - Bankroll management, staking strategies, and financial planning for bettors.

---

## All Links

- Homepage: https://getarbitragebets.com
- Free Arbitrage Finder: https://getarbitragebets.com/free-arbitrage
- Cross-Market Arbitrage Demo: https://getarbitragebets.com/cross-market-arbitrage-demo
- Prediction Markets: https://getarbitragebets.com/prediction-markets
- Prediction Markets Arbitrage: https://getarbitragebets.com/prediction-markets-arbitrage
- Prediction Market Arbitrage Report 2026: https://getarbitragebets.com/reports/prediction-market-arbitrage-2026
- Arbitrage Betting: https://getarbitragebets.com/arbitrage-betting
- Arbitrage Calculator: https://getarbitragebets.com/arbitrage-calculator
- Odds Calculator: https://getarbitragebets.com/bettingoddscalculator
- Hedge Calculator: https://getarbitragebets.com/hedge-calculator-betting
- Compound Calculator: https://getarbitragebets.com/compound-calculator
- Future Picks: https://getarbitragebets.com/future-picks
- Pricing: https://getarbitragebets.com/pricing
- Blog: https://getarbitragebets.com/blog
- Contact: https://getarbitragebets.com/contact
- Affiliates: https://getarbitragebets.com/affiliates
- Courses: https://getarbitragebets.com/courses
- Privacy: https://getarbitragebets.com/privacy
- Terms: https://getarbitragebets.com/terms
- Twitter/X: https://x.com/ArbBets_Agent

## Last Updated

2026-08-04