Legality in California
Both are CFTC-regulated and legal in all 50 US states including California. Novig operates as a peer-to-peer exchange; Sleeper operates event contracts inside its broader sports-and-fantasy app. No state-level differentiation.
Markets and coverage
Sleeper covers NFL, NBA, MLB, NHL, soccer (including World Cup 2026), and select cultural markets — broad sports coverage anchored to fantasy. Novig is sports-focused too — NFL, NBA, MLB, NHL, college, soccer, tennis and golf majors — with an exchange-style order book. Neither covers politics or macro; for that, Kalshi is required.
Pricing & fees
Novig's peer-to-peer structure often produces tighter prices on liquid sports markets — no house margin, just bid-ask spreads. Sleeper's pricing is competitive but operates more like a traditional event-contract book. Both charge small per-contract fees disclosed at order entry.
User experience
Sleeper's interface is built for fantasy users — your league, draft, chat, and trades in one app. Novig's interface is built for traders — visible order books, limit orders, bid-ask spreads. Sleeper is friendlier for casuals; Novig rewards traders who understand exchange mechanics.
Who should use which
Use Sleeper if: you already use it for fantasy, you want trading and social in one app, you're a casual or intermediate sports fan. Use Novig if: you're an experienced sports trader, you've been limited or banned by sportsbooks, you want the tightest pricing on high-liquidity markets. Many California traders use Sleeper as their daily app and Novig as a specialist edge tool.