Best Prediction Market Arbitrage Tools & Software (2026)

TL;DR

The best prediction market arbitrage tools scan Polymarket, Kalshi, and Opinion simultaneously, match identical events across platforms, and calculate net profit after fees. ArbBets leads for cross-platform scanning and API access (990+ markets, 100+ daily opportunities, 1–8% typical ROI). Predictions Terminal is the strongest all-in-one terminal. Arbitrage Agent and Claw Arbs focus on automated execution. Open-source tools like EdgeHunt and ArbIt are useful for learning but require engineering time. Manual scanning misses most opportunities because spreads often close within minutes.

Last updated: July 4, 2026

What We Evaluated

We ranked tools on five criteria that matter for real cross-platform arbitrage — not just headline prices:

1. Multi-platform coverage — Does it scan Polymarket, Kalshi, and Opinion (or at least two) at once?
2. Market matching — Can it link the same real-world event across different contract titles?
3. Fee-adjusted math — Does it account for Kalshi taker fees, slippage, and orderbook depth?
4. Speed — Real-time or WebSocket feeds vs. delayed polling?
5. API / automation — Can developers build bots, alerts, or agents on top?

Best Prediction Market Arbitrage Tools Compared (2026)

According to ArbBets scan data (July 2026), the platform monitors 990+ matched markets across Polymarket, Kalshi, and Opinion and surfaces 100+ arbitrage opportunities per day. Most opportunities yield 1–8% ROI after Kalshi fees. Average opportunity window is 2–6 hours in normal conditions; during high-volatility events, spreads can close in minutes.

— Source: ArbBets real-time market data

Tool Breakdown

1. ArbBets — Best Overall for Cross-Platform Arbitrage

ArbBets is purpose-built for prediction market arbitrage. It continuously scans orderbooks on Polymarket, Kalshi, and Opinion, matches equivalent contracts, and shows fee-adjusted spread, max profitable size, and per-platform cost breakdown.

Key features:

• 990+ markets monitored across politics, crypto, economics, sports events, and entertainment
• Orderbook-aware fills — walks full ask depth, not just top-of-book
• Kalshi fee model built in — 7% taker fee calculated on actual fill price
• 100+ daily opportunities — most yield 1–8% net ROI
• REST API (Premium) — normalized pairs, orderbooks, and pre-computed arbs for trading agents
• Category filters — Sports, Politics, Crypto, Finance, Tech, Economy

Best for: Traders who want the deepest Polymarket + Kalshi + Opinion coverage without building matching logic themselves. Developers building prediction market bots who need a data layer.

Pros:

• Only major scanner with simultaneous three-platform coverage
• Fee-adjusted profit and investment calculator
• Endorsed by prediction market traders; Kalshi CEO Tarek Mansour has publicly supported the category

Cons:

• Scan-and-alert model — you execute trades manually (or via your own bot using the API)
• Not a full terminal (no whale tracker, news scoring, or social features)
• Pro plan does not include API; Premium required for automation

Pricing: Pro $149/month (scanner). Premium $299/month (scanner + API, 5,000 credits/month).

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2. Predictions Terminal — Best All-in-One Terminal

Predictions Terminal is a professional dashboard for Polymarket and Kalshi traders. Its arbitrage scanner is one of 20+ tools in a broader terminal — whale tracking, AI news scoring, leaderboards, and paper trading included.

Best for: Traders who want one screen for research, sentiment, and arbitrage — not just a dedicated arb feed.

Pros:

• Strong UX and broad feature set beyond arbitrage
• Arbitrage module calculates profit after fees and slippage
• Lower entry price (~$49/month Pro) than full-stack scanners

Cons:

• Arbitrage is one feature among many — less depth than arb-first tools on matching and sizing
• API/automation story is lighter than ArbBets Premium
• Includes sportsbook data — may distract if you only trade prediction markets

Pricing: Free tier available; Pro approximately $49/month (verify on site).

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3. Arbitrage Agent — Best for Automated Execution

Arbitrage Agent is an execution-focused system for Polymarket and Kalshi. It pairs markets with embedding-based matching, streams prices over WebSocket, and fires both legs in parallel with a circuit breaker if one side fails.

Best for: Traders with capital on both platforms who want hands-off two-leg execution, not just alerts.

Pros:

• True automated execution with unwind logic
• High-precision market matching (thousands of linked titles)
• Kelly sizing and live-editable risk parameters

Cons:

• Requires API keys and comfort with automated capital deployment
• Narrower scope than a full scanner terminal
• Higher operational complexity than manual tools

Pricing: Paid subscription tiers (verify current plans on site).

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4. Claw Arbs — Best for Multi-Venue Automated Execution

Claw Arbs detects and executes arbitrage across prediction markets and other venues via WebSocket feeds and platform APIs. It targets sub-second detection and API-based order placement on Kalshi and Polymarket.

Best for: Technical traders who want detection and execution in one system across multiple venue types.

Pros:

• Automated execution on API-enabled platforms
• WebSocket feeds for Kalshi and Polymarket
• Built for low-latency workflows

Cons:

• Broader venue scope means less prediction-market-specific depth than ArbBets
• Steeper setup than a pure scanner
• Pricing and venue list change frequently — verify before subscribing

Pricing: Varies by plan (verify on site).

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5. EdgeHunt — Best Free Open-Source Analytics

EdgeHunt is an open-source CLI for cross-venue arbitrage detection, fee-adjusted EV, Kelly sizing, and fair-value mispricing signals on Kalshi and Polymarket-style markets.

Best for: Developers learning arbitrage math who want transparent, local, fee-aware calculations before paying for a hosted scanner.

Pros:

• Free and auditable source code
• Real Kalshi and Polymarket fee models in the engine
• Good for understanding Kelly and break-even math

Cons:

• Live adapters are still maturing — not a turnkey production scanner
• No hosted alerts, matching at scale, or mobile access
• You maintain infrastructure yourself

Pricing: Free (open source).

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6. ArbIt — Best for Research and Simulation

ArbIt is an open-source quantitative pipeline for detecting and simulating risk-free arbitrage across Polymarket, Kalshi, Manifold, and other platforms. Strong on backtesting and basket construction logic.

Best for: Quants validating arbitrage strategies on historical data before going live.

Pros:

• Full pipeline: ingest → match → validate → simulate PnL
• Multi-platform normalized schema
• No subscription cost

Cons:

• Research/simulation focus — not a daily trading dashboard
• Significant engineering required to run in production
• Live execution is DIY

Pricing: Free (open source).

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7. DIY Spreadsheet + Platform APIs — Best for Custom Builders

Roll your own tracker using Kalshi's API, Polymarket's CLOB API, and Opinion's endpoints.

Best for: Engineers who need bespoke alerts, internal dashboards, or proprietary matching rules.

Pros:

• Full control over logic and integrations
• No monthly software fee (only your time)

Cons:

• Market matching across platforms is the hard part — titles rarely align
• APIs change; maintenance is ongoing
• You will not match the scan breadth of 990+ markets without serious investment

Pricing: Free tools; high time cost.

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8. Manual Tab Comparison — Best for Learning

Open Polymarket, Kalshi, and Opinion side by side. Search for the same event. Calculate whether YES on one platform plus NO on another costs less than $1.00.

Best for: Your first week understanding how prediction market arbitrage works.

Pros: Free. Builds intuition for fees, settlement, and execution.

Cons: Does not scale. Misses 95%+ of opportunities. Error-prone on fee math.

How to Choose the Right Tool

What Makes a Good Arbitrage Scanner?

Multi-platform coverage

Arbitrage requires price differences between exchanges. A tool that only watches Polymarket cannot find cross-platform spreads. Minimum viable coverage is two platforms; three (Polymarket + Kalshi + Opinion) dramatically expands the opportunity set. See our three-way platform comparison.

Accurate market matching

The same event is phrased differently on each platform:

• Kalshi: "Fed cuts 25bps in May"
• Polymarket: "Will the Fed cut rates at the May FOMC?"

Text matching fails. Production tools use semantic matching, embeddings, or human-curated pair lists. A false match is worse than a missed opportunity.

Fee-adjusted calculations

Kalshi charges a taker fee based on contract price. Polymarket has no trading fee but may have spread costs. A 3% gross spread can become 0% or negative after fees. Tools must show net ROI. Learn the math in how to calculate arbitrage.

Speed

Typical opportunity timeline:

Polling every 5 minutes is not enough for competitive arbitrage. Real-time or WebSocket feeds are essential.

Pricing: What Does It Cost to Break Even?

Most active traders capture 10–30+ opportunities per month. A single well-sized cross-platform arb often covers a month of subscription cost.

Getting Started

Step 1: Fund accounts on each platform

Before any tool helps, you need capital ready on:

• Polymarket — USDC wallet on Polygon
• Kalshi — USD via bank or debit (US residents)
• Opinion — USD or crypto depending on account setup

Compare platforms in our best prediction market platforms guide.

Step 2: Pick a tool matching your skill level

• Beginner: Manual comparison → ArbBets Pro
• Developer: ArbBets Premium API or open-source stack
• Automation-first: Arbitrage Agent or Claw Arbs

Step 3: Start with small position sizes

Use $50–$100 per leg until you are comfortable with execution speed, fee math, and settlement timing. Scale once your process is consistent.

Step 4: Track results

Log gross spread, fees, fill price, and net PnL per trade. Review weekly to see which market categories (politics, crypto, sports events) produce the most opportunities.

Frequently Asked Questions

Related Reading

• Prediction markets arbitrage guide — step-by-step walkthrough
• Polymarket vs Kalshi vs Opinion — platform comparison for traders
• Best prediction market platforms — where to open accounts
• Prediction market bots — building automated agents
• How to calculate arbitrage — fee-adjusted math explained

Start Finding Opportunities

The prediction market arbitrage space is expanding as Polymarket, Kalshi, and Opinion add markets and volume. Manual comparison worked when dozens of markets existed. With 990+ matchable contracts today, automated scanners are essential for capturing meaningful returns.