Interact with Ethereum and EVM chains using type-safe TypeScript clients for reads, writes, and ABI encoding.
npx skills add https://github.com/andresdefi/cryptoskills --skill viem-andresdefi
Please help me install this Agent Skill. Skill: viem Source: https://github.com/andresdefi/cryptoskills/tree/main/skills/viem Command: npx skills add https://github.com/andresdefi/cryptoskills --skill viem-andresdefi
as const assertions, including the simulate-then-execute pattern that catches reverts before spending gas. - Client Architecture: Configure PublicClient for reads, WalletClient for writes, and TestClient for local nodes, with HTTP, WebSocket, and fallback transports across 50+ built-in chain definitions. - Batching and Utilities: Batch reads via Multicall3, encode/decode ABI calldata, convert between wei/gwei/ether with bigint, and handle errors through the BaseError walk pattern. - Use Case: Build a dApp backend that checks ERC-20 balances across multiple tokens in one RPC call, approves a spender only when allowance is insufficient, and executes a swap with gas estimation and revert handling. ## Quick Start Ask the agent to create a viem public client for Ethereum mainnet and read the USDC balance of a given wallet address.High-intent search queries and answers about installing and using this skill.
Use createPublicClient with a chain and transport, then call readContract with the contract address, ABI, function name, and args. Define the ABI with an as const assertion so TypeScript infers argument and return types automatically.
viem uses native bigint instead of BigNumber, splits functionality into PublicClient and WalletClient instead of Provider and Signer, and requires explicit chain and transport configuration. ABIs need as const assertions for type inference, and simulation is separated from execution.
Create a WalletClient with an account, chain, and transport, then call sendTransaction for ETH transfers or simulateContract followed by writeContract for contract calls. Always simulate first to catch reverts before spending gas, then check the receipt status.
Yes, viem ships definitions for 50+ chains including Arbitrum, Optimism, Base, Polygon, zkSync, and Scroll, importable from viem/chains. For unsupported networks, use defineChain to specify the chain ID, RPC URLs, native currency, and block explorer.
This error means the contract call reverted on-chain, usually from insufficient balance, missing approval, or invalid arguments. Catch it via err.walk() on a BaseError to access the decoded custom error name and arguments from revertError.data.
Use client.multicall with an array of contract call configurations, which routes through the Multicall3 contract in a single RPC round-trip. By default allowFailure is true, so each result includes a status field indicating success or failure.
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