Yes. Parlaid is free and runs on free, keyless public data (ESPN, nflverse, Polymarket). No account, no sportsbook login, no API keys.

Type a conditional bet rule — league, bet type, side, entry point, and the conditions that must hold at entry. Parlaid replays the rule across every qualifying game with a flat stake and reports the return per bet, the sample size, and the caveats in full.

NFL, NBA, and MLB are live today, fully backtestable game by game. Every other sport in the "More sports ▾" menu — college football, college basketball, soccer, combat sports, tennis, and more — is capture_ready, not backtestable yet: Parlaid lists it honestly with its current status instead of showing fake controls. A sport comes online once its line-history and results data have accrued enough to price and grade bets honestly; at that point it moves from the More menu to a full tab with real backtests, presets, and a leaderboard, the same as NFL, NBA, and MLB today.

NFL and NBA games, kept fully separate: moneyline, spread, and total bets at pregame or in-game entry points, plus team-prop and player-prop backtests (e.g. a team's giveaways/takeaways or a player's rushing yards, over/under a line), all priced against real market data including Polymarket prediction-market prices. MLB is also live, currently limited to run-total (over/under) bets at pregame entry plus runs-based team props — MLB has no player props yet and no in-game entry, so those controls are hidden rather than shown broken.

Giveaways are turnovers your own team commits (interceptions thrown, fumbles lost). Takeaways are turnovers your defense forces from the opponent — the same underlying data, viewed from the other side of the ball.

Parlaid prints the caveats most backtests hide: sample sizes, flat-stake assumptions, and lower-confidence data eras isolated in the report. Backtested returns are past results, not predictions.

Free, keyless public sources: ESPN box scores, nflverse play-by-play, and Polymarket prediction-market prices.

The Bet Slip is global and cross-sport: add a custom game, team-prop, or player-prop leg in Parlay Lab — which has its own League select, independent of the top sport tabs — or send a finished Backtest straight to your slip. Legs from different sports sit side by side, each tagged with a league badge, and switching the top NFL/NBA/MLB tab never clears the slip or resets Parlay Lab. You don't need Parlay Lab to build a parlay, either: the Backtest page has its own "+ Add leg to slip" button next to Run it, so you can add several rules from the same league (or different ones) straight from the builder — no run required first. One leg in the slip runs solo as a single Backtest; 2–5 legs backtest as a combined parlay — press "Backtest parlay" from the Backtest page and the combined report renders right there (Parlay Lab stays the standalone cross-sport workspace; pressing it from Parlay Lab still reports there). Either way Parlaid shows the combined American-style price, per-leg pricing tiers, and the independence/same-game caveats (plus a cross-sport caveat when legs span more than one league) in full.

Only rules that beat 0% ROI: strategies the house seeded plus community submissions. Every submission is re-run through the backtest engine on the server before ranking — a submission that comes back unprofitable doesn't make the board, and the app shows you that result rather than hiding it.

Yes — "Build it with AI" on Backtest, Parlay Lab, and TradeBin turns a plain-English description (e.g. "bet the under on turnovers every jets game" or "buy yes under 20 cents on weather markets") into a validated bet rule ready to run. Claude Haiku parses it when the site has a key configured; otherwise a deterministic keyword parser — team names, stats, over/under lines, player names, categories, price bands — does the same job and says so. Either way, every parsed bet is checked against the exact same rules the manual builder enforces before it's ever shown to you.

TradeBin backtests rule-based strategies over RESOLVED Kalshi and Polymarket event-binary (yes/no) markets — economic data prints, weather, awards, entertainment, politics, crypto prices, and more. It's a standalone section, separate from the sports engine: pick a source (any, Kalshi, or Polymarket), a category, a side (yes/no), a price band in cents, and how many days before close to enter, and TradeBin replays that rule over every matching resolved market with the same honesty rules as Backtest — sample size, fee drag, liquidity realism, and a category-mining warning printed in full.

No. Binary event contracts settle through completely different machinery (yes/no resolution, per-contract fees, no shared game context) from the sports moneyline/spread/total/prop bets the Bet Slip and Parlay Lab combine — so TradeBin rules stay in their own section and their own leaderboard board, never mixed into a parlay.

Yes — a TradeBin report is tagged "REAL SETTLEMENT · EST. FEES" rather than a sports pricing tier, because the entry price is an actual quoted market price at the time you chose (not a sportsbook line or a modeled approximation). Kalshi bets carry Kalshi's real per-contract taker fee; Polymarket bets are modeled fee-free here — mixing both in one rule is flagged as a cost-basis caveat whenever it happens.