Transparency
Provably fair coin flips on Solana
Every Cointoss.gg result can be independently checked. We commit to a secret before you bet, then reveal it after the flip so the outcome cannot be changed mid-round. The flip is a fair 50/50 draw; the site edge is only in the 1.9× win payout (5% house edge).
How verification works
- Server seed hash — shown before the round locks so the seed is fixed in advance.
- Client seed — derived when betting locks, mixed into the result calculation.
- Reveal — after the flip, the server seed is published.
- Check — hash the revealed seed, confirm it matches the pre-round commitment, then recompute the flip.
Why this matters
Without a pre-commitment, a house could in theory pick a result after seeing bets. Publishing a hash first makes that impossible without detection: any changed seed would produce a different hash.
House edge vs fairness
Provably fair means the heads/tails outcome is committed and verifiable — not that payouts are 1:1. Winners are paid 1.9× their stake (not 2.00×), which is a 5% house edge over time. Example: bet 100 coins and win → you receive 190 coins total.
Where to verify in the app
On the live game page, open the Provably Fair panel under the coin. You’ll see the upcoming server seed hash, client seed details, and the last reveal for completed rounds.
API for developers
Public endpoints are available for automation and audits:
GET /api/provably-fair— current commitment and recent revealsGET /api/provably-fair/:roundNumber/verify— verify a specific roundGET /api/flip-stats— recent heads/tails distribution