Backtest
Build a conditional bet rule and replay it across every qualifying game — with the caveats printed in full.
Props are settled pregame — in-game entry/condition controls don't apply.
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Backtests the flat-stake rule across every qualifying game. "+ Add leg to slip" sends the current rule to the parlay slip without running it.
Prediction Market
Trade a real Polymarket contract price in-game: buy an entry condition, then exit at a target, exit at a stop, or hold to settlement — instead of a one-shot bet. NFL and NBA only; MLB has no local prediction-market price data, so it says so instead of faking a report.
Parlay Lab
Build a leg from any league — its own League select, independent of the sport tabs above — from a preset or from scratch: game lines, team props, or player props. Every leg goes to the parlay slip; run one alone or 2–5 together as a combined parlay.
Positive-ROI strategies — the board
Only rules that beat 0% ROI make this board: house-seeded strategies plus community submissions, ranked by ROI per bet. Every rule shown here re-ran the backtest engine before it was allowed on.
Each row on the board names a rule in plain language and reports its ROI per bet, hit rate, sample size (N), and whether it's a house-seeded strategy or a community submission — ranked by ROI per bet, highest first. NFL, NBA, and MLB each keep their own board; switch sport tabs above to see a different one.
Leaderboard storage is ephemeral — entries may be reset on redeploy. Open this tab to load the current board.
Your runs
Every backtest and parlay you run is saved here automatically, newest first. Re-run one to get the full report back — the saved copy keeps the headline numbers, not the equity curve.
Paper-betting bots
Promote a pregame backtest into a simulated bot that places flat-stake paper bets on upcoming games and tracks a bankroll. No real money, no real wagers, ever.
Real-money sportsbook betting Coming soon
The bots above are paper-only by construction: the bot engine has no sportsbook connection and no real-money code path in it at all. Handing a strategy's picks to your own sportsbook account is on the roadmap, with no date attached — and it would not change what Parlaid is. Parlaid is not a sportsbook, and takes no bets: a real wager stays yours to place, in your own account, at your own book.
FAQ
Is Parlaid free?
Yes. Parlaid is free and runs on free, keyless public data (ESPN, nflverse, Polymarket). No account, no sportsbook login, no API keys.
How do I backtest a sports betting strategy?
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 P&L per bet, the sample size, and the caveats in full.
Which sports can I backtest?
NFL, NBA, and MLB are live today, fully backtestable game by game. Every other sport on the More sports page — 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 that page to a full tab with real backtests, presets, and a leaderboard, the same as NFL, NBA, and MLB today.
Which leagues and bet types can I backtest?
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.
What's the difference between giveaways and takeaways?
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.
Can I trust the backtested results?
Parlaid prints the caveats most backtests hide: sample sizes, flat-stake assumptions, and lower-confidence data eras isolated in the report. Backtested results are past results, not predictions.
Where does the data come from?
Free, keyless public sources: ESPN box scores, nflverse play-by-play, and Polymarket prediction-market prices.
What is the Parlay slip / Parlay Lab?
The parlay 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.
What does the "Positive-ROI strategies" board show?
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 at or below 0% ROI doesn't make the board, and the app shows you that result rather than hiding it.
Can I type my bet in plain English?
Yes — "Build it with AI" on Backtest and Parlay Lab turns a plain-English description (e.g. "bet the under on turnovers every jets game") 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 — 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.