Platform Identity
Polymarket
Hybrid Decentralized · Founded 2020
A hybrid-decentralized prediction market where order matching is handled off-chain but settlement is enforced on-chain via Polygon smart contracts. USDC-collateralized. Markets are curated by the team but settled transparently via UMA's Optimistic Oracle. Returned to US users via regulated brokerages (CFTC approval) in late 2025.
Kalshi
Fully Centralized · Founded 2018
America's first CFTC-licensed Designated Contract Market (DCM) for event contracts. Operates as a fully centralized, regulated exchange — no blockchain, no crypto required. Users fund accounts in USD. Kalshi selects and lists all markets, which must meet CFTC regulatory standards. Raised $1B at an $11B valuation in Dec 2025.
Rain Protocol
Fully Decentralized · Launched Nov 2025
A permissionless prediction market infrastructure layer built on Arbitrum — think "Uniswap for prediction markets." Anyone can create public or private markets without gatekeeper approval. Provides SDKs, APIs, and smart contracts for builders. Resolution handled by an AI-hybrid oracle system (Delphi + Lex). Native $RAIN token governs the DAO.
Technical Architecture — Trade Lifecycle
Polymarket
CLOB + Polygon
1
Sign Order (EIP-712)User signs a cryptographic order via their wallet. No gas paid per order.
2
Off-chain CLOB MatchingSigned order sent to Polymarket's off-chain Central Limit Order Book. Matching happens in <200ms.
3
On-chain Settlement (Polygon)CTF Exchange smart contract (ERC-1155) performs atomic swap of conditional tokens vs USDC.e. Relayer batches gas costs.
4
Resolution via UMA OracleOutcome submitted to UMA's Optimistic Oracle. Disputed outcomes go through a decentralized dispute process.
5
Auto-settlementWinning conditional tokens redeemable 1:1 for USDC. Smart contracts enforce final payout.
Kalshi
Centralized DCM
1
Account Funding (USD)Deposit via ACH, wire, or card. No crypto wallet required. Fiat held in segregated accounts per CFTC rules.
2
Limit or Market OrderUser places quick (market) or limit order on a Yes/No binary contract. Prices range $0.01–$0.99 = implied probability.
3
Centralized Order MatchingKalshi's own matching engine pairs buyers and sellers peer-to-peer. No house edge — Kalshi is a neutral exchange.
4
CFTC-Regulated ClearingKalshi holds both DCM and DCO licenses. All clearing follows Commodity Exchange Act rules. Surveillance for insider trading enforced.
5
Cash Settlement (USD)Winning contracts pay $1.00. Losers pay $0. Settled directly to account balance. Withdraw via ACH or wire.
Rain Protocol
AMM + Arbitrum
1
Deposit (USDT/USDC/ETH)Deposit stablecoins or ETH over Arbitrum, Ethereum, Base, or BNB Chain. Account abstraction smooths the UX.
2
Market Creation (Permissionless)Anyone creates a market — public or private — using the SDK or UI. No approval needed. Builders can deploy via SDK/API.
3
AMM TradingAutomated Market Maker provides continuous liquidity. Dynamic pricing based on participant conviction. Enter or exit positions at any time.
4
AI-Hybrid Oracle ResolutionDelphi (multi-AI agents) verifies outcome data. Lex (AI judge) issues initial ruling. Challenged? Escalates to human oracle panel. Dispute bond: min(0.1% of volume, $1000).
5
On-chain Settlement (Arbitrum)Smart contracts execute final payout in USDT. $RAIN token burned from fee revenue via buyback mechanism.
Technical & Financial Comparison
| Parameter | Polymarket | Kalshi | Rain Protocol |
|---|---|---|---|
| Model | Hybrid decentralized Off-chain order book |
Fully centralized Regulated DCM |
Fully decentralized Protocol / infra layer |
| Blockchain | Polygon PoS (Chain ID 137) ERC-1155 conditional tokens |
None — traditional fintech stack | Arbitrum L2 Multi-chain deposits (ETH, Base, BNB) |
| Order Mechanism | CLOB V2 — off-chain matching, on-chain atomic settlement via CTF Exchange contract | Centralized matching engine, peer-to-peer order book, no house edge | Automated Market Maker (AMM) — continuous liquidity, dynamic pricing |
| Collateral / Currency | USDC.e (bridged USDC on Polygon) | USD (fiat) — ACH, wire, debit card | USDT primary; USDC, ETH, BNB accepted |
| Oracle / Resolution | UMA Optimistic Oracle — decentralized dispute resolution | Internal Kalshi team + data providers; CFTC-supervised | Delphi (multi-AI agents) → Lex (AI judge) → Human oracle panel escalation |
| Market Creation | Curated by Polymarket team only | Curated by Kalshi; must meet CFTC approval standards | Fully permissionless — anyone can create public or private markets |
| Regulatory Status | Unregulated globally; US access restored via CFTC-approved brokerages (Oct 2025) | CFTC Designated Contract Market (DCM) + Derivatives Clearing Org (DCO) — federally licensed | Unregulated; global access, no KYC at protocol layer |
| KYC / Geo-fencing | Geo-blocked US users until Oct 2025 brokerage workaround; crypto wallet required | Full KYC required; US-only currently; no crypto wallet needed | No KYC at protocol level; wallet required; global access |
| Trading Fees | Maker: 0% · Taker: ~2% Gas abstracted via relayer batching |
Maker: ~1.75% · Taker: ~7% Fee = multiplier × p × (1−p) |
AMM spread + protocol fee; portion burned via $RAIN buyback |
| Native Token | None (USDC only) | None (USD fiat) | $RAIN — DAO governance + trading power access + deflationary burn |
| Private Markets | No | No | Yes — first platform to enable private, invite-only prediction markets |
| Developer Access | CLOB API, REST, WebSocket; open order book data | REST API for market data and trading | SDK, APIs, smart contracts; "machine-readable" for AI agent integration |
Financial Scale (2025 Full-Year & Current)
Polymarket
2025 Annual Volume
~$220B
Nov 2025 Monthly Vol
$3.74B
Latest Valuation
$9–15B
Key Investors
ICE / NYSE parent ($2B)
Market Share
~48%
Kalshi
2025 Annual Volume
~$238B
Nov 2025 Monthly Vol
$5.8B
Latest Valuation
$11B
Key Investors
Sequoia, a16z, Paradigm
Market Share
~50%
Rain Protocol
Cumulative Volume
$18M+
TVL
~$4M
Active Users
28,000+
Launch Date
Nov 6, 2025 (beta)
Notable Treasury
Enlivex $212M RAIN buy
Best Fit
Polymarket
Use when you need
The largest variety of global markets with the deepest crypto-native liquidity. Best for traders comfortable with USDC wallets who want low maker fees, programmatic access via CLOB API, and maximum market breadth across geopolitics, sports, crypto, and culture.
Kalshi
Use when you need
Regulatory certainty and fiat-native access. Best for US-based retail traders, institutions, or anyone who needs CFTC-regulated derivative exposure to real-world events with a traditional brokerage experience — no crypto wallet required. Taker fees are higher but regulatory clarity is unmatched.
Rain Protocol
Use when you need
Infrastructure to build on, or niche/private markets not possible elsewhere. Best for developers, DAOs, and communities wanting to deploy custom prediction markets without seeking approval — including private, invite-only forecasting for organizations. Still early-stage; liquidity is a fraction of the duopoly.