> For the complete documentation index, see [llms.txt](https://docs.manifold.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.manifold.xyz/client-sdk/sdk/public-provider-adapters/viem.md).

# Viem

**createPublicProviderViem(publicClients, fallbackProviders?)** → IPublicProvider

Creates a public provider from Viem public clients with optional fallback support.

## Parameters

| Parameter     | Type                                             | Required | Description                               |
| ------------- | ------------------------------------------------ | -------- | ----------------------------------------- |
| publicClients | Record\<number, PublicClient \| PublicClient\[]> | ✅        | Map of network IDs to Viem public clients |

## Examples

### Basic usage

```typescript
import { createPublicProviderViem } from '@manifoldxyz/client-sdk';
import { createPublicClient, http } from 'viem';
import { mainnet, base, optimism } from 'viem/chains';

// Create public clients for each network
const publicClients = {
  1: createPublicClient({
    chain: mainnet,
    transport: http('YOUR_MAINNET_RPC_URL')
  }),
  8453: createPublicClient({
    chain: base,
    transport: http('YOUR_BASE_RPC_URL')
  }),
  10: createPublicClient({
    chain: optimism,
    transport: http('YOUR_OPTIMISM_RPC_URL')
  })
};

// Create the public provider
const publicProvider = createPublicProviderViem(publicClients);

// Use with Manifold client
const client = createClient({ publicProvider });
```

### With fallback providers

```typescript
import { createPublicProviderViem } from '@manifoldxyz/client-sdk';
import { createPublicClient, http } from 'viem';
import { mainnet, base } from 'viem/chains';

// Providers with fallback (used when primary fails or is on wrong network)
const publicClients = {
  1: [
  createPublicClient({
    chain: mainnet,
    transport: http('PRIMARY_MAINNET_RPC_URL')
  }),
  createPublicClient({
    chain: mainnet,
    transport: http('FALLBACK_MAINNET_RPC_URL')
  })
  ]
};

// Create the public provider with fallback support
const publicProvider = createPublicProviderViem(publicClients);

// Use with Manifold client
const client = createClient({ publicProvider });
```

## Browser usage

For browser applications using MetaMask or other injected wallets:

```typescript
import { createPublicProviderViem } from '@manifoldxyz/client-sdk';
import { createPublicClient, custom } from 'viem';
import { mainnet } from 'viem/chains';

// Use the browser's injected provider
const publicClient = createPublicClient({
  chain: mainnet,
  transport: custom(window.ethereum)
});

const publicProvider = createPublicProviderViem({
  1: publicClient
});

const client = createClient({ publicProvider });
```

## Event Subscription

Subscribe to contract events in real-time using the `subscribeToContractEvents` method:

```typescript
import { createPublicProviderViem } from '@manifoldxyz/client-sdk';
import { createPublicClient, http } from 'viem';
import { mainnet } from 'viem/chains';

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

const publicProvider = createPublicProviderViem({
  1: publicClient
});

// Subscribe to Transfer events
const unsubscribe = await publicProvider.subscribeToContractEvents({
  contractAddress: '0x...',
  abi: erc20Abi,
  networkId: 1,
  topics: ['0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef'], // Transfer event signature
  callback: (log) => {
    console.log('Transfer event:', log);
  }
});

// Later: unsubscribe from events
unsubscribe();
```