How 90Picks Works

90Picks uses a parimutuel model — the same system used by horse racing and tote betting for over 150 years. There are no fixed odds and no bookmaker. Instead:

1. Pick a side — Home, Draw, or Away for any World Cup match
2. Put dollars in — Your dollars go into the match pot (minimum $1, maximum $10,000)
3. Winners split the pot — After the match, everyone who picked correctly splits the total pot proportionally

The less popular your pick, the bigger the payout if you win. All multipliers shown during the open phase are estimates (marked with ~). Final payouts are determined only when betting closes, 30 minutes before kickoff.

The system has three components:

Users (Coinbase Smart Wallet)
    │
    ├── deposit / claim
    │
    ▼
Frontend (Next.js on Vercel)
    │
    ├── reads pool data + sends transactions
    │
    ▼
Base L2 Blockchain
    │
    ├── PoolFactory → creates MatchPool per match
    ├── MatchPool #1 (Mexico vs Canada)
    ├── MatchPool #2 (USA vs Morocco)
    └── MatchPool #N ...
          │
          ├── resolve() ← CRE Resolver (polls match results)
          └── cancel()  ← CRE Resolver or Owner

Base L2 provides sub-cent gas costs and fast finality. All transactions are sponsored by the Coinbase paymaster — users never need to hold ETH or pay gas fees.

Two Solidity contracts, built with OpenZeppelin:

Key Functions

Constants

[CREATED] ──deposit()──▶ [OPEN] ──deadline──▶ [CLOSED]
                                                    │
                                         resolve() or cancel()
                                                    │
                                    ┌───────────────┼───────────────┐
                                    ▼                               ▼
                              [RESOLVED]                      [CANCELLED]
                                    │                               │
                                claim()                         claim()
                              (winners)                       (full refund)
                                    │
                             collectFees()
                            (after 7 days)
                                    │
                               sweep()
                           (after 90 days)

• Open phase: Users can deposit until 30 minutes before kickoff
• No withdrawals: Bets lock at deposit — this prevents odds manipulation
• 90-minute result: Only the 90-minute score counts. Extra time and penalties don't affect the outcome — Draw is always a valid pick
• Safety valve: If the automated resolver fails, the owner can resolve manually after 48 hours

A 2.5% fee is charged on losing pools only. Winners' deposits are never taxed.

Example: $10,000 total pot
  Home: $6,000 (60%)  ←  wins
  Draw: $1,500 (15%)
  Away: $2,500 (25%)

Losing pool = $4,000 (Draw + Away)
Fee = $4,000 × 2.5% = $100
Distributable to winners = $9,900

A $100 bet on Home → payout = $9,900 × ($100 / $6,000) = $165

Referral Rebate

If a user was referred, they receive a 50% rebate on their proportional fee share. The rebate comes from the platform fee — it does not affect other users' payouts.

• OpenZeppelin libraries — ReentrancyGuard on deposit/claim, SafeERC20 for all USDC transfers. Battle-tested, industry-standard.
• Key separation — Three distinct roles with different permissions: Factory Owner (creates pools, emergency controls), CRE Resolver (resolves/cancels matches), and Users (deposit/claim only). Compromise of one key doesn't give full control.
• Safety valves — Owner can cancel any pool for full refunds. Manual resolution available after 48-hour waiting period. Fee collection delayed 7 days after resolution for claim window.
• No admin withdrawal — There is no function for the owner to withdraw user deposits. The only outflows are claim() (to users), collectFees() (to fee recipient, after 7 days), and sweep() (dust cleanup after 90 days).
• Deterministic addresses — Pool addresses are derived from match IDs via CREATE2. Anyone can verify a pool's authenticity on-chain.

59 tests covering all contract functions, edge cases, and mathematical invariants. Built with Foundry (Forge).

Coverage

• Deposit flows — valid deposits, boundary amounts ($1 / $10,000), referral tracking, paused pool, closed pool, invalid outcomes
• Resolution — CRE resolve, manual resolve (48h delay), resolve with all three outcomes, resolution when one outcome has zero deposits
• Cancellation — CRE cancel, owner cancel, full refund verification
• Claims — winner payouts, proportional math, double-claim prevention, refunds on cancel
• Fee math — 2.5% calculation, referral rebate deduction, fee collection timing (7-day window), zero-fee edge cases
• Invariant testing — conservation of funds (payout + fees = totalPool), cancel = exact refund, fee bounds, double-claim prevention, referral rebate conservation
• Sweep — 90-day timing, dust recovery, unauthorized access

Source code: github.com/djehuty94/Golazo

Contract addresses will be published here once mainnet deployment is complete.

Individual MatchPool addresses are deterministic — derived from the match ID via CREATE2. Once pools are created, each match page will link directly to its contract on BaseScan.