ContractReader.io

ContractReader.io is a web tool for reading and understanding smart contracts deployed on Ethereum and compatible networks. Paste a contract address or a block explorer URL and it renders the verified source with syntax highlighting, shows live on chain values alongside the code, and lets you compare two versions of a contract in the browser. It supports Ethereum mainnet, Sepolia, OP Mainnet, Polygon, Arbitrum One, BNB Smart Chain and Base. It is for developers, auditors and anyone who wants to check what a contract does before interacting with it. The core reader is free to use without an account. The AI functionality sits in a separate audit tool, currently in beta and open for signups, which adds private code pages, pasting of raw code, imports from testnets, access control through ENS names, on chain value visualization, annotated comments, direct read and write interaction with contracts, and security reviews generated by an OpenAI GPT model. No pricing is published for either the reader or the audit tool; the audit tool is reached by joining the beta list. The product is maintained by a two person team with a public GitHub presence and a Discord community, which is worth knowing for buyers who need vendor support commitments rather than community help.