> ## Documentation Index
> Fetch the complete documentation index at: https://blockscout-ap-erc-8056-envs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Multichain Service

> Aggregate hashes, tokens, and addresses across chains behind one Blockscout endpoint for unified search, token discovery, and multichain UX.

The Multichain service aggregates hashes and entities from multiple chains behind one endpoint.

* single search across chains
* token discovery without chain selection
* unified UX for hashes

| Handle                                                                                                        | What it gives you                                                                               | Why it is useful                                        |
| ------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------- | ------------------------------------------------------- |
| `GET https://api.blockscout.com/multichain/api/v1/clusters/multichain/chains`                                 | List of chains supported by Multichain service                                                  | Required to know which chains are indexed in multichain |
| `GET https://api.blockscout.com/multichain/api/v1/clusters/multichain/search:quick?q={query}&apikey=YOUR_KEY` | Multichain search results for addresses, blocks, transactions, tokens, NFTs, domains, and dapps | One search box across all supported chains              |

## Examples

### Multichain token search

Use for:

* token discovery across all supported chains
* resolving multiple deployments (e.g. USDC on Ethereum, Arbitrum, Base)
* showing correct contract per chain

```bash theme={null}
curl "https://api.blockscout.com/multichain/api/v1/clusters/multichain/search:quick?q=usdc&apikey=YOUR_KEY"
```

### Multichain address / tx lookup

Use for:

* detecting which chain an address or transaction belongs to
* building a universal search bar
* avoiding chain selection UX

**Example (address):**

```bash theme={null}
curl "https://api.blockscout.com/multichain/api/v1/clusters/multichain/search:quick?q=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&apikey=YOUR_KEY"
```

**Example (transaction):**

```bash theme={null}
curl "https://api.blockscout.com/multichain/api/v1/clusters/multichain/search:quick?q=0x4b03d69654a965de6a2fe907856a0e39a51a8ae25d9ddb8d97aa16ba5c1835e1&apikey=YOUR_KEY"
```

## Minimal flow

1. fetch supported chains

```bash theme={null}
curl "https://api.blockscout.com/multichain/api/v1/clusters/multichain/chains?apikey=YOUR_KEY"
```

2. user inputs query
3. call `search:quick`
4. render results grouped by type + chain

## TypeScript example

```ts theme={null}
const API_KEY = process.env.BLOCKSCOUT_API_KEY ?? "YOUR_KEY";
const QUERY = process.argv[2] ?? "usdc";

const base = "https://api.blockscout.com/multichain/api/v1/clusters/multichain";

async function getJson(url: string) {
  const res = await fetch(url);
  return res.json();
}

async function main() {
  const chains = await getJson(`${base}/chains?apikey=${API_KEY}`);
  console.log("Supported chains:", Object.keys(chains).length);

  const searchUrl =
    `${base}/search:quick?q=${encodeURIComponent(QUERY)}&apikey=${API_KEY}`;

  const data = await getJson(searchUrl);

  console.log(`\nQuery: ${QUERY}\n`);

  for (const token of data.tokens ?? []) {
    const chains = Object.keys(token.chain_infos ?? {});
    console.log(`${token.symbol} | ${token.address_hash}`);
    console.log(`chains: ${chains.join(", ")}`);
  }

  console.log("\nAddresses:", (data.addresses ?? []).length);
  console.log("Transactions:", (data.transactions ?? []).length);
}

main();
```

## Supported chains

Fetch dynamically:

```bash theme={null}
GET https://api.blockscout.com/multichain/api/v1/clusters/multichain/chains
```

***