How do you build a market with more than two possible answers on Rain?
Every market is a pool, and each possible answer inside it is a sub-pool that trades as its own Yes or No.
Take "Who will win the league?"
Every team gets its own sub-pool, with its own price and its own result.
For builders, that means one structure for every market your platform runs, from a single yes/no to a full list of outcomes.
One question, as many answers as it needs.
Rain
Permissionless prediction market infrastructure on Arbitrum with dual AMM and order-book trading
3.0/ 5
Our score
Fair
What is Rain?
Rain is a permissionless prediction market protocol built on Arbitrum that allows developers and individuals to create, trade, and settle customized event markets. By providing both automated market maker pools and order-book routing, the protocol lets participants trade binary and categorical outcomes directly through self-custodial smart contracts.
Team and governance
The protocol was founded by Roy Shaham. The underlying smart-contract infrastructure and developer tooling are maintained via the rain1-labs GitHub organization. The protocol incorporates a native token under the ticker RAIN to coordinate network participants across its ecosystem.
Trading mechanics and market architecture
Rain structures each outcome market as an independent liquidity pool. For complex markets with more than two possible answers, each outcome operates as a sub-pool trading as a distinct Yes or No position. Traders hold continuous exposure by purchasing outcome shares that can be exited prior to resolution or held until event settlement. Trading can occur against constant AMM liquidity or through an order book where traders quote specific buy and sell prices to one another. Wallet interactions and gas execution are coordinated through modular components, including RainAA for account abstraction.
Fee model and incentives
Traders pay a 5% fee on every executed transaction. The protocol redistributes this fee among three key participants that sustain each market: liquidity providers who back the trading pool, the creator who configures and launches the event, and the designated resolver responsible for outcome determination.
Audits and track record
In August 2025, security firm Hacken audited Rain's token smart contract. By October 2026, total value locked in the protocol reached approximately $15.9M on Arbitrum.
Risk factors and settlement trade-offs
Because the protocol allows independent market creation and third-party resolvers, traders face risks around oracle accuracy and resolution disputes. Thin liquidity in newly generated or niche sub-pools can lead to high slippage. The 5% transaction fee is relatively steep compared to standard decentralized exchange swaps.
Founders
Roy ShahamFounder
Best for:Arbitrum DeFi tradersIndependent prediction market creatorsDevelopers building event platformsTraders seeking un-KYC'd event contracts
Pros and cons
Pros
- Permissionless market creation without approval steps or forms
- Dual AMM and order-book options accommodate both niche and liquid markets
- Token contract audited by Hacken in August 2025
- TVL reached over $15.8M on Arbitrum in October 2026
Cons
- Fixed 5% trading fee is high compared to standard DeFi swaps
- Third-party resolvers introduce potential event dispute risks
- Operation is confined to Arbitrum with no other chains supported
- Niche sub-pools risk thin liquidity and execution slippage
Our review
3.0/5
Fair
Rain delivers permissionless market creation and dual AMM and order-book trading on Arbitrum, but its 5% trading fee is steep.
Rain operates as decentralized prediction market infrastructure deployed on Arbitrum, where developers and traders can launch custom event markets without approval steps. Founded by Roy Shaham, the protocol combines an automated market maker pool with an order book. That dual design ensures immediate quotes for niche outcomes while letting traders set specific buy and sell prices when order flow allows.
For liquidity, the protocol held $15.9M in total value locked in October 2026. Rain structures multi-outcome markets into modular pools where each possible outcome operates as an individual Yes-or-No sub-pool. Transactions can be routed through an account abstraction layer known as RainAA, which abstracts gas handling and derives a smart account from the user's connected Web3 wallet. Smart contract security is anchored in part by a smart contract audit conducted by Hacken on its token contract in August 2025.
The primary trade-off sits with costs: Rain charges a standard 5% fee on every trade. That fee is distributed among pool liquidity providers, the market creator, and the designated resolver settling the event. While this revenue split creates financial incentives for third-party platforms to build on top of the SDK, a 5% baseline haircut is significantly higher than conventional decentralized exchanges and makes rapid, high-frequency trading expensive.
Rain suits developers building specialized forecasting interfaces and niche prediction communities that require permissionless event creation on Arbitrum.
Sources (2)
Specs
| Chains | Arbitrum |
|---|---|
| Trading fees | 5% per trade split across LP, creator, and resolver · unverified |
| Resolution source | Designated market resolver · unverified |
| Liquidity rewards | Yes · unverified |
Not disclosed by the provider: Market types, Settles in, Available in the US, KYC required, Regulated venue, Market topics, Mobile app.
Data from the provider's website and public sources. Fees and availability change; confirm on the official site before you sign up.
Key features
Dual execution models
Supports continuous AMM pools for instant execution alongside order books for limit-order trading between peers.
Arbitrum settlement
Executes all market transactions and smart contracts on the Arbitrum network to minimize gas overhead.
Categorical outcome sub-pools
Structures multi-outcome events into modular sub-pools where each outcome trades as an independent Yes or No contract.
Three-way fee distribution
Levies a 5% fee on trades and routes portions to the market creator, the resolver, and liquidity providers.
Account abstraction integration
Uses RainAA to derive smart accounts from user wallets and manage transaction signing without holding user private keys.
Stateless developer SDK
Offers an SDK that generates unsigned transactions without custody or key-management requirements.
Inside Rain
AMM Pools
Automated market maker liquidity pools that automatically quote continuous prices so traders can buy or sell positions immediately without waiting for a counterparty.
Order Book
A peer-to-peer matching mechanism where users can quote each other directly and specify the exact purchase or sale price for market shares.
RainAA
An account abstraction module that derives a smart account from the user's wallet to handle gas sponsorship and transaction execution.
Rain SDK
A developer toolkit and machine-readable framework that allows teams and automated agents to deploy and integrate custom prediction market platforms.
What users say about Rain
There is virtually no detailed user feedback available for Rain. The few mentions only refer to it as an open prediction market protocol without offering substantive reviews.
Based on 8 Reddit posts and comments from the last 12 months, checked Oct 20, 2026. These are posts by users on other sites, not reviews submitted on CryptoReview.
User reviews
No user reviews yet. Have you used Rain? Share your experience below.
FAQ
Who founded Rain?
Rain was founded by Roy Shaham. The protocol operates decentralized prediction market infrastructure on Arbitrum.
What fees does Rain charge on trades?
Traders pay a 5% fee on every trade. This fee is divided between liquidity providers, market creators, and the resolver settling the market.
What chains does Rain support?
Rain runs natively on the Arbitrum network. Users trade and interact with contracts through compatible Arbitrum wallets.
Does Rain have a token?
Yes, Rain has an associated token with the symbol RAIN. The RAIN token contract completed an audit by Hacken in August 2025.
How does market resolution work on Rain?
Markets allocate a portion of trading fees to a designated resolver who settles the outcome. Each outcome in a multi-choice market settles individually as a Yes or No result.
Latest from Rain on X
How does a platform on Rain make money?
Traders pay a 5% fee on every trade and the protocol splits that fee between the roles that make a market work: the liquidity providers who fund the pool, the creator who launches the market, and the resolver who settles the outcome.
Run every role yourself, or share them with your users. Your platform, your call.
Traders pay a 5% fee on every trade and the protocol splits that fee between the roles that make a market work: the liquidity providers who fund the pool, the creator who launches the market, and the resolver who settles the outcome.
Run every role yourself, or share them with your users. Your platform, your call.
Every market has to answer one question: who's on the other side of your trade?
Rain has two answers.
The AMM is a pool that always quotes a price. You trade against it directly, and the price moves with every trade. No waiting for a counterparty, which matters most in new and niche markets where one might not exist yet.
The order book is traders quoting each other. Set the exact price you'll buy or sell at, and your order sits onchain until someone takes it. Sharper pricing where there's real activity.
Rain gives builders both. Quiet markets stay tradeable, busy markets stay tight, and your platform calls the same SDK either way.
Rain has two answers.
The AMM is a pool that always quotes a price. You trade against it directly, and the price moves with every trade. No waiting for a counterparty, which matters most in new and niche markets where one might not exist yet.
The order book is traders quoting each other. Set the exact price you'll buy or sell at, and your order sits onchain until someone takes it. Sharper pricing where there's real activity.
Rain gives builders both. Quiet markets stay tradeable, busy markets stay tight, and your platform calls the same SDK either way.
Rain is global prediction markets infrastructure.
Anyone, anywhere, any language. https://t.co/2AHPgxBUqV
Anyone, anywhere, any language. https://t.co/2AHPgxBUqV
👀 https://t.co/QGJr8ulOXk
Recent public posts from @Rain__Protocol, shown as published. Not reviewed or endorsed by CryptoReview.
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