Odds

Understanding History and Market Movers

• Historical odds are tracked up to 72 hours in the past
• For exchange-style platforms, odds are calculated with assumed $100 stake
• Historical comparisons use the current prematch event list. For example, when setting timeframe to 72 hours ago, an event must have been tracked at that time to be considered. If tracking began only 48 hours ago, the event will not appear in the comparison.
• When identifying the biggest market movers, movement on exchange-style platforms is excluded when it results solely from a tightening bid–ask spread rather than a genuine change in market pricing

• The scraped odds are limited to moneyline, spread, and total markets. While all betting platforms are scraped for moneyline odds, whether spreads and totals—including alternate lines—are scraped depends on the operator and sport.
• Odds are collected directly from the sportsbooks and exchanges themselves through public APIs, WebSocket feeds, and browser-based scraping when required.
• Odds from each betting platform are continuously refreshed on a rolling scraping cycle every 90 seconds.
• This tool is designed primarily for pre-match odds comparison and market analysis. It is not intended or reliable for live betting, where prices can change rapidly and may move multiple times between refresh cycles, on top of the time it takes you to place a wager.
• For tennis in particular, the query logic already accounts for the different settlement and retirement rules used by various sportsbooks. That means ATP and WTA suggestions are grouped and filtered so the live query results are only comparing books that have compatible settlement rules.
• For traditional state-regulated sportsbooks, mainline markets are generally very similar across jurisdictions, although minor differences do occur. Said differently, the odds for a market on DraftKings New York can technically be different from the odds on DraftKings Illinois, though instances like these on main markets are very rare. For traditional state-regulated sportsbooks operating in multiple states, the odds on their New Jersey platform are gathered. This is because New Jersey has one of the largest and most widely supported sports betting markets in the United States, with every traditional sportsbook that operates in multiple states available there. A consequence of using New Jersey as the reference jurisdiction is that some events available there may not be offered in your state's version of the same sportsbook. This is most commonly seen with college sporting events, which can be restricted in a team's home state. Additionally, because individual state regulatory bodies dictate their own sports wagering catalogs, the availability of lower-volume or niche markets is decided by state law rather than a sportsbook's internal trading policies. For example, New Jersey permits sportsbooks to offer the full spectrum of professional tennis, including ATP Challenger and WTA 125K events, whereas New York's stricter regulatory catalog explicitly bans these lower-tier markets entirely.
• For exchange-style platforms, the best displayed price is not always the price that can actually be obtained for a larger wager. Order books contain limited liquidity at each price level, so increasing the wager size may require consuming additional liquidity deeper in the book at progressively worse prices. To account for this, effective odds are calculated using the available order book liquidity rather than simply the best quoted price. These calculations are performed at stake levels of $100, $150, $200, ..., up to $3,000, with applicable taker fees already factored in, and the appropriate value is selected automatically based on the stake and hedge requirements specified in the query.
• Kalshi and Gemini list some equivalent outcomes in separate, unlinked markets—for example, buying Yes on Team A to win and buying No on Team B to win may produce the same payoff but draw from different order books. Effective odds reflect the optimal execution available across all routes while assuming that liquidity at the same price across equivalent outcomes may come from the same algorithmic trader. In other words, if that trader has linked asks on both Yes Team A and the equivalent No Team B outcome, filling their ask on one route may cause their corresponding ask on the other route to be removed rather than representing additional independent liquidity.
• FanDuel sometimes lists different odds for its mainline spread or total and the same line in its alternate spread or total markets. When this occurs, the higher of the two odds is stored. two.
• Deciding which leagues to scrape is an ongoing process. Because adding additional leagues is often relatively straightforward, future expansion will likely include a wider range of markets, potentially including player props and smaller international leagues. For now, however, I have prioritized popular mainline betting markets that generally have liquid and easily hedged counterparts across sportsbooks. As a result, I do not currently emphasize markets such as golf tournament winners or many soccer markets, where hedging can be more complex due to the possibility of draws. At present, my scraper covers the four major U.S. sports leagues (NFL, NBA, MLB, and NHL), along with the WNBA, UFC, ATP and WTA events across multiple tour levels, and a variety of NCAA sports including football, men's and women's basketball, and baseball.