Arbitrage Betting Discussion

An arbitrage opportunity exists when the combined implied probability of all outcomes of an event — priced at different bookmakers — adds up to less than 100%. Backing every outcome at those prices costs less than the total payout, guaranteeing a profit regardless of the result. The gap between your total stake and guaranteed return is the arb margin.

Divide 100 by the decimal odds. A price of 2.50 carries an implied probability of 100 ÷ 2.50 = 40%. Sum the implied probabilities of all outcomes: if they total less than 100%, an arb exists. If they total exactly 100%, the bookmaker breaks even. Any figure above 100% is the bookmaker overround — there is no arb.

On high-liquidity markets such as NFL, Premier League, and ATP tennis, practical arbs run between 0.5% and 3% gross. Niche sports, lower leagues, and markets with fewer competing bookmakers can produce 5–10% margins but close faster. A realistic working assumption for planning is 1.5–2% average margin across a mixed portfolio of markets.

Bookmakers set odds independently, using different pricing models, different liability positions, and different information flows. They also adjust lines at different speeds in response to market movement or team news. These independent pricing decisions create persistent gaps — particularly in the period between a market opening and the event going live.

A two-way arb covers two outcomes (moneyline, tennis, basketball). A three-way arb covers three outcomes — home win, draw, away win in soccer. The three-way calculation adds a third implied-probability term to the sum. Three-way arbs require three separate placements and are slightly more complex to execute, but the draw outcome in soccer is frequently the most mispriced, creating regular opportunities.

Yes, immediately. If Bookmaker A shortens their price on one outcome after you spot an arb, the combined implied probability increases and the margin shrinks or disappears entirely. This is why timing matters: the arb that existed 60 seconds ago may no longer exist when you go to place. Always verify both prices on-screen before placing either leg.

Overround is the bookmaker's built-in margin — the amount by which the sum of implied probabilities exceeds 100%. A book with 105% implied probability total has a 5% overround. Arbing exploits situations where two different books' overrounds happen to land on opposite sides of an event, producing a gap. You are not beating the overround of any individual bookmaker — you are arbitraging the difference between two independent pricing decisions.

For a two-outcome arb: Stake on Side A = Total stake × (1/OddsA) ÷ (1/OddsA + 1/OddsB). The same principle extends to three outcomes. Most arb tools calculate this automatically and display the exact amounts. When placing manually, use the formula or a calculator — then round to the nearest $5–$10 before placing to avoid sharp-bettor profiling.

A middle is a scenario where two bookmakers price a spread or total line far enough apart that there is a range of outcomes where both bets simultaneously win. It is not a guaranteed profit like a standard arb — the middle only pays out if the result lands in the overlap range — but if the middle hits, both bets win and the return is substantially higher than a standard arb margin.

No. Arbs are most common on sports with deep bookmaker competition: soccer (especially European leagues), tennis, basketball, and American football. Sports with fewer bookmakers competing on the same event produce fewer and shorter-lived arbs. Niche sports (esports, minor-league baseball, lower-division soccer) can produce higher margins but have lower liquidity and smaller accepted stake sizes.

Pre-match arbs appear before an event starts and can persist for hours. Live arbs appear during an event and can close within seconds because odds move rapidly in-play. Live arbing requires fast execution and a tool with a high-frequency scanner. Pre-match arbing is more forgiving for beginners and suitable for manual execution.

Yes, if new arb opportunities appear as bookmakers update their lines. A pre-match arb on an NFL game might produce three separate opportunities as bookmakers adjust prices over the week before kick-off. Each is a distinct arb — independent stakes, independent margin. Your exposure management should ensure that your total stake across multiple arbs on the same event does not create an unwanted net directional position.

Closing line value (CLV) is the difference between the odds you took and the final odds when the market closes. For value bettors, beating the closing line is the primary performance metric. For arbers, CLV is less directly relevant — you are not predicting outcomes — but monitoring CLV helps verify that your tool is surfacing genuine market inefficiencies rather than stale or erroneous odds.

On major European soccer, NFL, or ATP tennis markets with thousands of active participants, arb windows can close in under 5 minutes during peak activity. Off-peak (midweek, minor matches), the same window might persist for 30–60 minutes. Live market arbs close in seconds to a minute. Your tool's refresh rate and your own execution speed determine how many opportunities you can realistically act on.

A soft bookmaker accepts recreational bettors, sets its own lines, and limits winning accounts. Most high-street and online operators in regulated markets are soft books. A sharp bookmaker (e.g. Pinnacle) accepts professional bettors, sets accurate lines calibrated to the true market, and does not limit winners. Arbs most commonly occur between two soft books, or between a soft book and an exchange.

No more than using any other information tool. Bookmakers use their own algorithmic pricing systems and risk management software. Using a scanner that reads publicly available odds and identifies gaps is legal and does not constitute fraud or cheating. Bookmakers' restriction of profitable accounts is a commercial decision — not a legal one — and is entirely separate from the legality of the activity.

Yes. Placing a back bet at a bookmaker and a lay bet on Betfair exchange on the same outcome is a valid arb structure. Exchange-backed arbs are particularly attractive because Betfair does not limit winning accounts. The exchange charges a commission on winning lays (typically 2–5%), which must be factored into the margin calculation before treating the opportunity as a real arb.

Stake rounding means placing $200 instead of the exact $197.43 the calculator outputs. The imprecision is small (typically under 0.3% margin loss) but the benefit is significant: rounded stakes look like recreational betting patterns, which slows account limiting at soft bookmakers. Always round down on the smaller leg to ensure you do not accidentally over-stake and create a net loss on one outcome.

Soccer is the single richest source globally — the sheer number of leagues, bookmakers, and time zones creates persistent pricing gaps. Tennis is second, particularly on mid-tier ATP/WTA tournaments where pricing updates are slower. In US markets, NFL moneylines and player props produce the most daily opportunities, followed by NBA. Totals and player props tend to have higher margins than moneylines on the same event.

If one leg of an arb is voided (due to a late scratch, rule 4 deduction, or market error), your other leg remains active. You are left with a one-sided directional position on the unvoided leg. The correct response is to immediately check whether you can hedge the exposure — lay the outcome on an exchange if possible, or place a matching bet at any available price to limit downside. This is one reason to always have exchange access alongside bookmaker accounts.

An arbitrage betting tool is a scanner that monitors bookmaker odds simultaneously, identifies pricing gaps, and alerts you to opportunities with calculated stake splits. Without one, you would need to manually compare dozens of bookmakers in real time — impractical when arb windows close in minutes. A tool automates the monitoring so you focus on evaluation and execution.

Scanners ingest live odds from bookmaker feeds — via official partnerships or frequent scraping — and normalise the data to a common format. The detection engine calculates implied probability sums across all covered outcomes in real time and flags any event where the total falls below 100%. The output is a ranked list of current opportunities with pre-calculated stake splits, refreshed continuously.

A live scanner monitors in-play markets and surfaces opportunities in real time, typically with windows of seconds to minutes. Pre-match alerts flag opportunities on upcoming events, sometimes days in advance. Live scanners require faster execution; pre-match alerts suit bettors who work on a schedule. Most professional tools offer both.

Start with bookmaker coverage: the tool must cover the sportsbooks you can legally access. US bettors need tools covering state-licensed operators (OddsJam, Outlier, Sharp). Global bettors need tools covering European and exchange markets (BetBurger, RebelBetting, Arbamigo). Then compare signal speed against your execution capacity, pricing against your bankroll, and free trial quality. Use /tools/best/ to match tools to your specific country and sport.

OddsJam is purpose-built for US state-licensed sportsbooks with the deepest US market coverage and a full API. BetBurger covers the widest global bookmaker count including middles detection. RebelBetting covers global markets and uniquely delivers both guaranteed surebets and Pinnacle-benchmarked value bets from a single subscription. The right choice depends entirely on which bookmakers you hold accounts with.

Yes — every major tool covered on this site offers a free trial. OddsShopper is permanently free for US markets. Most paid tools offer 7–14 day trials with full scanner access. Always run the trial on your actual bookmaker accounts to verify coverage before committing. The trial-period daily opportunity count on your specific books is the most reliable predictor of ongoing value.

Bookmaker coverage is the list of sportsbooks whose live odds the scanner monitors. A tool covering 80 bookmakers is only useful for the specific books you hold active accounts with. Filter every coverage claim to your own account list: five books you can access is worth more than 80 you cannot. Verify coverage during the free trial against your actual active accounts, not the total advertised book count.

Signal latency is the time between a mispricing appearing in the market and your tool surfacing it as an alert. Higher latency means you see the opportunity later, leaving less time to act before it closes. For live in-play arbs, latency of more than a few seconds can mean the arb is already gone by the time you see it. For pre-match arbs, latency matters less. Check how each tool measures and reports its update frequency.

Yes, and many professional arbers do. Running a US-focused scanner alongside a global one maximises daily opportunity volume across both market types. The combined cost should be recoverable against the incremental opportunities the second tool surfaces. Run both free trials simultaneously and measure the overlap — opportunities that appear on both tools are not doubled, so the net benefit is the unique opportunities each adds.

Value betting identifies single bets where a bookmaker's implied probability is lower than the true probability, producing positive expected value per bet. Unlike arbitrage, value bets can lose individually — the edge materialises across a large sample. Arbitrage guarantees a margin on every trade regardless of outcome. Tools like RebelBetting and OddsJam offer both surebetting and value betting signals from the same subscription.

A positive EV tool flags bets where the probability implied by the odds is lower than a reference sharp market consensus. OddsJam benchmarks against its own US market model; RebelBetting benchmarks against Pinnacle's closing line. Every identified bet is expected to be profitable over many repetitions — individual bets can still lose. EV tools require larger sample sizes and more patience than arb tools to assess performance.

Count actual daily actionable opportunities — arbs involving your specific books at your minimum margin threshold. Log them in a spreadsheet: tool, sport, books involved, margin, and whether you could have executed in time. After one week you have enough data to estimate monthly gross return at your bankroll. Compare that against the subscription price. Do not evaluate a trial by the total alert volume — evaluate it by filtered, actionable results on your books.

A middles scanner identifies markets where two bookmakers price a spread or total far enough apart that a specific range of outcomes makes both bets simultaneous winners. BetBurger includes a dedicated middles endpoint alongside its standard surebet feed. Middles require understanding of spread mechanics and careful EV calculation before acting — the "both win" scenario only occurs in the overlap range, not on every result.

Coverage varies significantly by tool. Arbamigo specialises in UK horse racing with Betfair exchange integration. BetBurger covers the widest range of sports globally. Most US tools focus on the four major leagues plus college sports. Before subscribing, verify that the specific sport and market type you want to arb is covered in the trial — horse racing, tennis, and combat sports each have different coverage profiles.

The stake calculator takes your total deployment amount and the odds on each side and outputs the exact stake for each leg so that every possible outcome returns the same gross amount. This is essential: placing equal stakes on both sides of a two-way market does not guarantee equal returns unless the odds are identical (which they never are in an arb). Most tools display the calculated split alongside each alert.

Sharp is a US-focused arbitrage and line shopping tool with dedicated iOS and Android apps. It is the only tool reviewed on this site with native mobile apps and push notifications for live arb alerts. Sharp is best for US bettors who primarily place bets on a mobile device and want a streamlined app-native workflow rather than a desktop web dashboard.

OddsShopper is a free US arbitrage and odds comparison tool. It covers major US state-licensed sportsbooks with no subscription cost. It lacks some of the advanced filtering, API access, and limiting-safety guidance of paid tools, but it is a legitimate starting point for US bettors learning the workflow before committing to a paid scanner.

Tools surface opportunities; they do not manage your bookmaker relationships. Some tools include stake-rounding guidance (round down to nearest $5/$10 before placing), exchange-backed arb flags (which reduce soft-book exposure), and notes on markets with higher limiting risk. The actual mitigation is behavioural — mixing in recreational bets, varying stake amounts, and spreading volume across many accounts — not tool-dependent.

Arbamigo is purpose-built for UK bettors with dedicated Betfair exchange integration, horse racing coverage, and commission-aware stake calculations. RebelBetting and BetBurger also cover UK markets with exchange-backed arbs in their global feeds. For pure Betfair-exchange arbing (exchange vs. exchange or exchange vs. sharp books), a specialist Betfair tool or the exchange's own API is more appropriate.

Yes, but the operational complexity is significant. You would need to ingest odds from each bookmaker (via API where available, or via scraping), normalise event names and market types across sources, run the detection logic, manage rate limits, and maintain the infrastructure continuously. For most bettors, a subscription scanner is far more cost-effective. Building your own makes sense if you want programmatic control, custom filters, or integration with placement automation — see the API section for data feed options.

Bookmakers cannot ban you from arbitrage betting itself — the activity is legal. However, they can refuse to accept your bets, reduce your maximum stake, or close your account for any commercial reason under their terms of service. This is called account limiting and it is standard industry practice for profitable accounts. It is not illegal and is entirely separate from the legality of arbing.

At aggressive soft bookmakers (especially US state-licensed operators), active arbers can face stake restrictions within 2–8 weeks of consistent activity. At European soft books, the timeline is often 2–6 months. Exchange accounts (Betfair, Smarkets) are not limited. The timeline depends on stake sizes, bet frequency, market selection, and whether you include any recreational betting activity to dilute the pattern.

The most effective tactics are: round your stakes to the nearest $5/$10 (avoid exact calculator outputs); include occasional small recreational bets on popular markets; vary your stake amounts slightly rather than always using the same amount; avoid betting on every single arb at a bookmaker (introduce some selection); and open accounts at as many operators as possible so limiting at one does not significantly reduce your total capacity.

Betting exchanges (Betfair, Smarkets, Betdaq) do not limit winners — they profit from commission on both sides of every market. Sharp bookmakers (Pinnacle, BETDAQ) also accept winning bettors. Among soft books, tolerance varies by operator and region. US sportsbooks limit particularly aggressively because they use sophisticated player profiling. UK-licensed books vary: some tolerate moderate arbing for years, others restrict within weeks.

A minimum of three active accounts is needed to see meaningful daily opportunity volume. Most active arbers maintain 10–20+ accounts across their accessible market. Open every account before you start active arbing — your window as an unrestricted new customer is finite. The account-opening phase is the highest-value period you will have with any bookmaker; do not squander it by opening accounts one at a time over months.

Yes — each account is held in your own name with your own identity. Using multiple accounts under the same name is legal and standard practice. You are not permitted to hold more than one account at the same bookmaker (multi-accounting), which is a terms-of-service violation. But holding one account each at 15 different bookmakers under your real identity is entirely standard.

Limiting reduces your maximum accepted stake — it does not freeze or confiscate your balance. You can still withdraw any funds in the account at any time. Once limited, you can still place recreational-sized bets (often $2–$10 maximum), which is sufficient for non-arbing activity but not for productive arbing. Some bettors keep limited accounts active for small recreational bets to maintain the account relationship.

Generally yes. US state-licensed sportsbooks operate under strict regulatory oversight, use sophisticated account profiling systems, and have short tolerances for systematic winning. Limits at DraftKings, FanDuel, or BetMGM can appear within weeks of consistent arbing. European soft books typically take longer to restrict, though this varies significantly by operator.

Yes, and it is one of the most limiting-safe strategies available. When one side of an arb is a Betfair lay (instead of a bookmaker back), only the bookmaker side carries limiting risk. Betfair profits from commission on both outcomes regardless of result. Exchange-backed arbs are available through tools like Arbamigo (UK) and RebelBetting (global). Betfair commission (typically 2–5% on winning lays) must be included in your margin calculation.

A Betfair lay is a bet against a selection winning — you are effectively acting as the bookmaker. If you lay Team A at 2.00 for £100, you collect £100 if Team A loses and pay out £100 if Team A wins. When combined with a back bet on Team A at a higher price at a traditional bookmaker, the two positions can create an arb margin. The Betfair commission on your winnings reduces the effective lay odds for calculation purposes.

Frequent large withdrawals can flag your account for manual review at some operators. Best practice is to maintain a working balance in each active account rather than withdrawing after every arb cycle. The balance acts as operational capital. Withdraw monthly rather than daily, and always ensure you meet any bonus wagering requirements before withdrawing if you accepted a bonus on that account.

In US states where sports betting is licensed, arbing at state-licensed sportsbooks is legal. There is no federal or state law prohibiting placing opposing bets at different licensed operators. The operators themselves may choose to limit your account, but that is a commercial decision, not a legal one. Verify that both operators you plan to use are licensed in your specific state before participating.

Sign-up bonus extraction (matched betting) involves using a bookmaker's welcome offer on one side of a market and laying the opposite outcome on an exchange, locking in 75–85% of the free bet value as cash. This is particularly valuable for new accounts where sign-up offers are most generous. Most serious arbers work through available bonuses first to build initial bankroll, then transition to pure arbing once bonuses are exhausted.

A mug bet (also called a recreational bet or decoy bet) is a small, non-arb bet placed to mimic recreational bettor behaviour. Bookmaker risk systems flag accounts that exclusively bet on large-margin, precisely-timed opportunities. A small occasional bet on a popular event — a £5 accumulator on Saturday Premier League matches, for instance — is sufficient to introduce some noise into your betting pattern and slow the profiling process.

Betfair Exchange, Smarkets, and Betdaq do not limit winners by design — they profit from commission on all bets. Pinnacle is the most famous sharp bookmaker that accepts professional bettors, though its odds are already sharp and arb opportunities against Pinnacle are rare. Some Asian handicap operators also have higher tolerance for winning accounts. For soft-book arbing, no mainstream operator actively welcomes it.

KYC (Know Your Customer) verification is a regulatory requirement at licensed bookmakers in most jurisdictions. Provide the requested documentation (government ID, proof of address, payment method verification) promptly. Delays can freeze your access to funds or withdrawals. KYC is not triggered by arbing — it is triggered by deposit or withdrawal thresholds, or random compliance checks. Have your documents ready before funding any new account.

Restriction (stake limiting) reduces your maximum accepted stake — you can still use the account for smaller bets and withdrawals. Account closure terminates the account entirely and requires you to withdraw your remaining balance. Closure is less common and usually reserved for cases of terms-of-service violations, not simply for being a profitable arber. Most bookmakers restrict rather than close.

No. Multi-accounting — holding more than one account at the same bookmaker — is a terms-of-service violation at every mainstream operator. Bookmakers share information through industry networks and verify identity via KYC processes. Attempting to circumvent a restriction by creating a new account is a serious breach that can result in permanent banning and potential forfeiture of any remaining balance.

A betting exchange matches bettors directly against each other rather than against the house. On Betfair, one user backs a selection and another lays it. The exchange takes a commission on winning bets from both sides and has no directional exposure to the outcome. Because there is no house liability, exchanges do not limit winners. Their available stake is limited only by the liquidity that other participants provide at the current price.

Limit tolerances are not publicly disclosed and change constantly. Generally, major European soft books (Bet365, Unibet) have higher initial stake limits than US sportsbooks before restrictions kick in. However, each bookmaker's profiling system operates independently. The only reliable way to know a specific operator's tolerance in your market is to track your own account history. Focus on opening many accounts rather than concentrating volume at one.

Prediction markets are exchanges where participants trade contracts that resolve to $1.00 (YES) or $0 (NO) based on a real-world event outcome. Prices between $0 and $1.00 represent the market's collective implied probability. Unlike sportsbooks, which set odds against bettors, prediction markets match buyers and sellers directly. The two major venues are Kalshi (US CFTC-regulated) and Polymarket (decentralised, Polygon blockchain).

The core mechanic is the same — find two venues pricing the same event such that the combined cost of covering both outcomes is below $1.00. The differences are structural: prediction markets settle based on formal resolution processes rather than sporting results, use different fee structures (Kalshi percentage-of-winnings, Polymarket CLOB spread/gas fees), and have thinner liquidity than major sportsbooks. Resolution risk — disputes about how a contract settles — is an additional risk not present in standard sports arbing.

Kalshi is a US prediction market operating as a CFTC-designated contract market (DCM) — the first federally regulated prediction exchange in the United States. It is legal for US participants, requires KYC verification, and operates in USD. Kalshi has faced legal challenges over specific market types (including US congressional election contracts) but the exchange itself has maintained its CFTC-regulated status. Regulatory status was current as of mid-2026; verify before participating.

Polymarket is a decentralised prediction market running on the Polygon blockchain, denominated in USDC. It does not require the same KYC verification as Kalshi. Polymarket has faced regulatory attention in the US — it settled with the CFTC in 2022 and its accessibility to US users has been restricted at various points. Its global regulatory status is unsettled. Verify current accessibility in your jurisdiction before participating.

For a YES/NO event: buy YES on one venue at price P_A cents and NO on the other at price P_B cents. Total cost = P_A + P_B. If P_A + P_B < 100 cents, a raw margin exists: 100 − (P_A + P_B). Subtract fees: Kalshi charges a percentage of winnings on the winning leg; Polymarket charges spread or gas. Net margin = raw margin − total fees. If net margin > 0, a real arb exists. Use our free calculator at /examples/ for the stake split.

Kalshi charges a percentage of winnings when a contract resolves in your favour. Fee tiers vary by market type and trading volume — higher-volume traders receive lower rates. Exact current fees are published by Kalshi. Always deduct Kalshi fees from your raw margin calculation before treating an opportunity as a real arb. A 3% gross margin that costs 2% in total fees is a 1% net arb — marginal but real.

Polymarket uses both CLOB (central limit order book) and AMM (automated market maker) markets. CLOB markets have bid-ask spreads; AMM markets have price impact proportional to position size versus pool depth. Polygon network gas fees are small but non-zero per transaction. For large positions on shallow AMM pools, slippage (the gap between quoted and executed price) is the main cost. Calculate effective fill price — not quoted price — before assessing any opportunity.

Resolution risk is the possibility that a contract resolves differently from how you expected based on a strict reading of the rules, or that the resolution itself is disputed. Kalshi uses defined outcome rules tied to verifiable official sources. Polymarket uses a decentralised UMA oracle that can be disputed. An arb that settles against you due to a resolution dispute produces a loss even if your combined cost was below $1.00. This risk is absent in standard two-outcome sports arbs.

For Polymarket, yes. Polymarket runs on Polygon and requires a USDC balance in an Ethereum-compatible wallet, or Polymarket's custodial option. You need to acquire USDC, potentially bridge it to Polygon, and connect your wallet. Kalshi operates entirely in USD with standard bank/card funding — no crypto required. If you are unfamiliar with self-custody crypto, Kalshi-only or Kalshi-sportsbook arbs avoid the wallet requirement entirely.

Prediction markets are significantly thinner than major sportsbooks. A $500 position on a major Kalshi election market may move the price by 1–2 cents, partially closing the arb before your order is fully filled. On Polymarket AMM pools, slippage scales directly with position size relative to pool depth. Always check the order book depth or pool size before sizing a position — the full notional at the quoted price is rarely available for large trades.

Yes, where the same underlying event is listed on both. A sporting event result priced as a YES/NO contract on Kalshi can be combined with a moneyline at a sportsbook covering the same game. Convert the moneyline to an implied probability percentage and compare with the Kalshi contract price. The challenge is ensuring the contract terms match exactly — a Kalshi "Will Team A win?" contract and a sportsbook moneyline must resolve on identical outcome criteria.

Major US political events (elections, Fed decisions) have the deepest liquidity on Kalshi and Polymarket and produce the most frequent cross-venue pricing gaps. Major sports championship outcomes are secondary. Macro events (CPI, employment data) also produce opportunities. The coverage of sports events is narrower on prediction markets than on sportsbooks — verify active markets on each platform before building a strategy around a specific event type.

PredictionHunt is an all-in-one finder monitoring Kalshi, Polymarket, and other venues simultaneously, surfacing cross-venue gaps with stake instructions. The Polymarket-Kalshi Arbitrage API Finder on Apify provides structured data for developers building automated systems. Both are covered in detail at /prediction-markets/. General-purpose arb scanners like OddsJam and BetBurger do not cover prediction markets.

On major election and macro-event markets with high participant counts, windows can close in under 60 seconds. On thinner markets with fewer active participants, opportunities can persist for minutes or longer. The practical implication is that manual execution requires having both venues open and ready before you act. Fully automated execution via API is more reliable for liquid markets.

Given fees and thin liquidity, small positions produce marginal absolute returns. A Kalshi-Polymarket arb with 2% gross margin and 1.5% combined fees nets 0.5% — on a $1,000 position that is $5 profit. A working position size for prediction market arbs is $1,000–$5,000 at edges above 1% net of fees. Below these levels, the dollar return per trade does not justify the operational complexity.

Tax treatment is jurisdiction-specific and unsettled for many markets. In the US, there are open questions about whether Kalshi contracts are section 1256 instruments (60/40 capital gains treatment) or ordinary income. Polymarket gains may be treated as cryptocurrency capital gains. This is not tax advice — consult a qualified tax professional familiar with derivatives and cryptocurrency before withdrawing significant profits from prediction market activity.

Yes. Kalshi offers a REST API and Polymarket has a CLOB API. An automated system can detect cross-venue gaps and place orders on both venues without manual intervention. Full automation introduces execution risk (partial fills if one side completes before the other), regulatory considerations for algorithmic trading on a CFTC-regulated venue, and smart contract interaction costs on Polymarket. Build and test thoroughly before deploying real capital.

Contract resolution ambiguity. In a standard two-outcome sportsbook arb, the resolution criteria are clear (Team A wins or Team B wins). In prediction markets, contracts can have ambiguous resolution language — "Will the Fed raise rates before December?" requires interpretation of what counts as "before". If the resolution oracle rules differently from your reading, your expected arb becomes a directional loss. Always read the exact contract resolution source and criteria before placing.

Market depth refers to how much volume is available at or near the current quoted price. On Polymarket's CLOB markets, the order book shows how many contracts are available at each price level. On AMM markets, depth is measured by the pool's total liquidity — deeper pools support larger trades with less price impact. Before placing a large position, check whether sufficient depth exists to fill your order at the expected price.

Yes. Smart contract risk (bugs in the contract code), oracle risk (the UMA resolution system ruling in unexpected ways), regulatory risk (the platform's US legal status is unsettled), and liquidity risk (thinner pools than centralised markets) are all specific to Polymarket's decentralised design. These risks are absent on regulated centralised venues like Kalshi. Participants should understand the blockchain infrastructure before committing meaningful capital to Polymarket positions.

An arbitrage betting API is a programmatic data feed that delivers real-time bookmaker odds and detected arb opportunities in structured JSON format. Instead of monitoring a browser dashboard, developers poll an API endpoint to retrieve current prices and opportunities, which they then filter, alert on, log, or route to automated execution systems.

Five providers are covered on this site: OddsJam (US sportsbooks, via /api/us-sportsbooks/), BetBurger (global bookmakers + middles, via /api/international-bookmakers/), RebelBetting (surebets + Pinnacle-benchmarked EV, via /api/sharp-betting/), SportsGameOdds (80+ bookmakers, AI-ready feed, via /api/ai-ready-odds/), and Breaking-Bet (all-sports coverage, via /api/all-sports/). See /api/ for the full comparison.

A REST API is a web service that responds to HTTP requests (GET, POST) with structured data — typically JSON. To use an arb API, you authenticate with your API key (sent in a request header), call the arb opportunities endpoint at your chosen polling interval, and parse the JSON response to extract the opportunity data. Most modern programming languages have HTTP libraries that make this straightforward.

Authentication is typically via a bearer token in the Authorization header: "Authorization: Bearer YOUR_API_KEY". Some APIs use a query parameter instead. Your API key is issued when you subscribe to an API-enabled plan and is available in your account dashboard. Keep it secret — treat it like a password. If it is compromised, regenerate it immediately from your account settings.

Rate limits cap how many requests your API key can make per second, minute, or hour. Exceeding them returns a 429 error and may temporarily block your key. For an arb pipeline, rate limits determine your minimum practical polling interval. If your limit is 1 request per 30 seconds, you cannot reliably catch arbs that open and close in under 30 seconds. Map your polling interval to your rate limit before building.

For pre-match arb data, polling every 60–120 seconds is usually sufficient. For live in-play data, poll as frequently as your rate limit allows — typically every 5–30 seconds on premium tiers. Rate limits for live data are often tighter than for pre-match. Check your plan's documented limits and set your interval 10–20% above the minimum to avoid accidental rate limit breaches during network latency spikes.

Each opportunity returned by the API includes a unique opportunity ID. Maintain a local set of seen IDs. On each poll, filter out any opportunity already in your set and process only new entries. Remove IDs from your set once they have expired (most APIs include a status field or timestamp indicating when an opportunity closed). This prevents the same opportunity triggering multiple alerts across consecutive polls.

Yes — this is one of the most common use cases. Poll the API on your chosen interval, filter results to your minimum margin and bookmaker list, and for each new opportunity call the Telegram Bot API (sendMessage) or a Discord webhook (POST with JSON payload) to deliver a formatted alert. Both platforms have simple HTTP webhook interfaces that require no special SDK. The alert message should include bookmaker names, odds, stake split at your standard size, and margin percentage.

n8n is a no-code/low-code workflow automation platform. You can use it to poll an arb API (HTTP Request node), filter results (Function or IF node), and send alerts (Telegram, Discord, Slack, or email node) without writing server code. n8n Cloud handles hosting. A basic arb alert workflow can be built and deployed in under two hours. It is the fastest path to a working automated pipeline for non-developers.

OddsJam's API is purpose-built for US state-licensed sportsbooks — it covers DraftKings, FanDuel, BetMGM, and similar operators with US-calibrated data including a positive EV endpoint. BetBurger's API covers the widest global bookmaker count, includes a middles detection endpoint, and serves developers building international pipelines. Choose based on which market your pipeline targets.

Yes — it is the only API in this guide that delivers both signal types from a single subscription. The surebets endpoint returns guaranteed arb margins. The value bets endpoint returns Pinnacle-benchmarked EV signals. Both are available via the same API key. Design your pipeline to route them to separate processing channels — surebets require immediate execution; value bets are informational and can be batched.

SportsGameOdds delivers normalised odds from 80+ bookmakers in a format designed for AI agent pipelines and multi-book monitoring systems. It is most useful for developers building aggregators, AI betting agents, or systems that need broad bookmaker coverage in a single data source rather than deep specialisation in one market (US or European). Confirm the exact current bookmaker count and sports coverage before building against it.

Breaking-Bet provides broad sports coverage beyond the major leagues that US-focused or European-focused APIs prioritise. It is most useful as a secondary provider in a pipeline that already uses OddsJam or BetBurger as the primary source — extending coverage into sports or markets not covered in depth elsewhere. Confirm specific coverage before building against it.

Storing opportunity data (bookmakers involved, odds at detection, margin, timestamp, and whether you acted) creates a performance log that lets you audit your strategy. Write each opportunity row to a database (Supabase, PlanetScale, SQLite) or a spreadsheet. After 500+ opportunities, you can measure: what your actual average margin is, which bookmaker pairs produce the most arbs, what time of day produces the highest volume, and whether your execution success rate matches expectations.

Yes, where bookmaker APIs exist. Betfair Exchange, some Asian operators, and a small number of European books offer placement APIs. US state-licensed sportsbooks do not offer public placement APIs. A full automation loop: detect arb via data API → validate margin → calculate stakes → place both legs via bookmaker API. Each layer introduces execution risk (partial fills, rejection codes, rate limits). Build and test incrementally — start with detection and alerts before adding automated placement.

Python is the most common choice — it has mature HTTP libraries (httpx, requests), good JSON handling, easy deployment via cloud functions, and a rich ecosystem for data storage and notification integrations. JavaScript/Node.js is a strong second option, particularly if you are building a web-based dashboard. For pure data processing at scale, Go or Rust offer better performance but have steeper learning curves. The language matters less than the architecture — a well-structured Python script outperforms a poorly structured Rust binary.

Normalisation means mapping each bookmaker's internal event IDs, team name formats, and market type labels to a consistent unified schema. Without it, "Arsenal vs Chelsea" on Betfair and "Chelsea vs Arsenal" on Bet365 are treated as different events by your comparison logic. All five APIs in this guide deliver normalised data — verify the normalisation depth for your specific markets (especially niche sports where normalisation quality varies) during your trial period.

No, in almost all cases. API provider terms of service typically prohibit redistributing or reselling raw data received via the API. You may build products on top of the data (alert services, dashboards, aggregated signals) but the underlying raw odds data cannot be passed to third parties as a raw feed. Read the terms of service for your chosen provider carefully before building any downstream data product.

Stale odds occur when the API response includes prices that have changed at the bookmaker since the last scrape. Compare the timestamp on each opportunity against your polling interval — if the data timestamp is older than 2× your polling interval, flag it as potentially stale. For live markets, reject any opportunity where the odds timestamp is more than 60 seconds old before acting. Include a re-verification step (check the current live price manually or via a second API call) for any opportunity above your minimum threshold.

A webhook is a push mechanism — instead of your server polling the API, the provider's server sends data to your endpoint when a new opportunity is detected. Some arb API providers support webhooks on premium tiers as an alternative to polling. Webhook delivery is faster (milliseconds vs. your polling interval) but requires your endpoint to be publicly accessible, handle bursty traffic, and be highly available. For most individual arbers, polling is simpler and reliable enough.