Everything you need to build on Rain

Rain is the decentralized prediction markets protocol on Arbitrum One, where anyone can create and trade markets on any topic. These docs cover the TypeScript SDK, REST & WebSocket APIs, and the upcoming fully on-chain CLOB.

Get Started SDK Reference CLOB — Coming Soon ⚡

bash

npm install rain-sdk-v2 viem

Explore the docs

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Getting Started

Install the SDK, pick an environment, and launch your first prediction market in 5 minutes.

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SDK Reference

Every transaction builder, read method, REST endpoint, and WebSocket event in rain-sdk-v2.

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Code Examples

Copy-paste TypeScript: create markets, trade, place limit orders, stream live prices.

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CLOB — Coming Soon

A fully on-chain central limit order book on an Arbitrum Orbit L3, with a Rust matching engine via Stylus.

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Components Status

What's live, what's in development, and what's planned across the Rain builder stack.

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Brand Assets

Official Rain logos, color palette, and usage guidelines for your integrations.

What is Rain?

Rain is a decentralized prediction markets protocol deployed on Arbitrum One. Markets ("pools") hold 2–26 options, and each option has a Yes and a No side that traders can buy, sell, split, and merge. Markets trade through an AMM or an on-chain order book, settle via AI or manual resolution with an on-chain dispute and appeal flow, and pay out winners directly from the market contract.

🔓 Permissionless markets

Anyone can create a market on any topic — set the question, options, liquidity, and resolution method.

📈 AMM + Order Book

Two trading models per market: continuous AMM pricing, or a price-time priority on-chain order book.

⚖️ On-chain resolution

AI or manual resolvers close markets, with bonded disputes and appeals enforced by contracts.

⛽ Gasless UX ready

Built-in Account Abstraction support (RainAA) with Alchemy paymaster gas sponsorship.

The builder stack

Component	What it gives you	Status
rain-sdk-v2	TypeScript transaction builders, on-chain reads, REST + WebSocket clients	Live
Protocol contracts	Markets, AMM, order book, resolution & disputes on Arbitrum One	Live
REST API + WebSocket	Pools, positions, orders, price history, realtime events	Live
On-chain CLOB (Orbit L3)	Fully on-chain matching engine in Rust/Stylus, CEX-grade performance	In Development

See the full components status page for the complete roadmap.