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What is Kleros?

Kleros is a decentralized dispute resolution protocol. Think of it as a court system for smart contracts - when parties disagree, Kleros provides a trustless way to reach an enforceable ruling. Kleros is implemented on Ethereum (V1) and Arbitrum (V2):
  • V1 is production infrastructure running on Ethereum Mainnet and Gnosis Chain. It has been in production since 2018 and continues to receive active development.
  • V2 operates on Arbitrum, with cross-chain support via the Vea bridge, modular dispute resolution via dispute kits, and improved scalability.
Each product section covers both V1 and V2. V1 integration guides and examples are included directly. V2 pages document technical specifications and contract references.

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Why Integrate?

Trustless Enforcement

No central authority. Rulings are cryptoeconomically secured by staked jurors.

Flexible Resolution

Binary yes/no, multiple choice, or nuanced rulings - your contract defines the options.

Cross-Chain Ready

Disputes can originate from Ethereum mainnet or other chains via the gateway system.

Battle-Tested

Over $50M in value secured through Kleros arbitration since 2018, with 100+ cases resolved on Court V2 Beta (September 2025).

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Use Cases

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How It Works (30-second version)

  1. Your contract implements the IArbitrableV2 interface
  2. When a dispute arises, call createDispute() with arbitration fees
  3. Random jurors are drawn (weighted by staked PNK)
  4. Jurors vote, with appeals possible
  5. The final ruling is passed back to your contract via rule()

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Next Steps

Quick Start

Get your first integration running in minutes

Architecture

Understand the protocol components

Products (V1 + V2)

Reference for every Kleros product