viem

name	viem
description	Viem blockchain client patterns for Ethereum interactions, transactions, signing, encoding, and smart contract calls. Triggers on viem, publicClient, walletClient, chain, abi.
triggers	viem, ox, publicClient, walletClient, transport, chain, abi, transaction, signature, encode, decode

Build blockchain interactions using viem for Ethereum clients, transactions, signing, and smart contract interactions. Viem is the modern replacement for ethers.js with better TypeScript support. **CRITICAL: Always fetch viem documentation before implementing.**

MCPSearch({ query: "select:mcp__plugin_devtools_context7__query-docs" })

// Client patterns
mcp__context7__query_docs({
  context7CompatibleLibraryID: "/wevm/viem",
  topic: "createPublicClient createWalletClient"
})

// Contract interactions
mcp__context7__query_docs({
  context7CompatibleLibraryID: "/wevm/viem",
  topic: "readContract writeContract simulateContract"
})

// Signing
mcp__context7__query_docs({
  context7CompatibleLibraryID: "/wevm/viem",
  topic: "signMessage signTypedData EIP-712"
})

// Encoding
mcp__context7__query_docs({
  context7CompatibleLibraryID: "/wevm/viem",
  topic: "encodeFunctionData decodeFunctionResult encodeAbiParameters"
})

**Create clients:**

import { createPublicClient, createWalletClient, http } from "viem";
import { mainnet } from "viem/chains";
import { privateKeyToAccount } from "viem/accounts";

const publicClient = createPublicClient({
  chain: mainnet,
  transport: http(),
});

const walletClient = createWalletClient({
  chain: mainnet,
  transport: http(),
  account: privateKeyToAccount("0x..."),
});

Read contract:

const balance = await publicClient.readContract({
  address: "0x...",
  abi: erc20Abi,
  functionName: "balanceOf",
  args: [userAddress],
});

Write contract:

const hash = await walletClient.writeContract({
  address: "0x...",
  abi: erc20Abi,
  functionName: "transfer",
  args: [recipient, amount],
});

const receipt = await publicClient.waitForTransactionReceipt({ hash });

| Client | Purpose | Example Use | |--------|---------|-------------| | `PublicClient` | Reading blockchain data | `getBlockNumber()`, `readContract()` | | `WalletClient` | Transaction signing/sending | `sendTransaction()`, `signMessage()` | | `TestClient` | Testing and simulation | `mine()`, `setBalance()` | | `BundlerClient` | ERC-4337 User Operations | `sendUserOperation()` | **Unit conversions:**

import { parseEther, formatEther, parseUnits, formatUnits } from "viem";

parseEther("1.5");           // 1500000000000000000n
formatEther(1500000000000000000n);  // "1.5"
parseUnits("100", 6);        // 100000000n (USDC)
formatUnits(100000000n, 6);  // "100"

Address utilities:

import { getAddress, isAddress } from "viem";

getAddress("0xabc...");  // Checksummed address
isAddress("0x...");      // Validates format

**Banned:** SSRF protection for config-sourced URLs (they're developer-controlled)

Required:

Lazy initialization for chain resolution
Client caching by network name
WebSocket cleanup on destroy/refresh
Type-safe ABI interactions

- [ ] Context7 docs fetched for current API - [ ] Uses lazy chain resolution - [ ] Caches clients by network name - [ ] Type-safe ABI interactions - [ ] Proper error handling for blockchain ops

Install Skill

SKILL.md