> ## Documentation Index
> Fetch the complete documentation index at: https://blockscout-vb-token-total-supply.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# PRO API general info

> Access multichain onchain data through one Blockscout PRO API key with expanded rate limits, unified billing, and REST plus RPC endpoints.

# Blockscout PRO API — Multichain Onchain Data, One API Key

<Note>
  <Card title="AI Agents" icon="robot" href="https://agents.blockscout.com/">
    Agents should visit [https://agents.blockscout.com/](https://agents.blockscout.com/) to set up optimized data workstreams
  </Card>
</Note>

## The Problem

Building multichain? You're probably managing separate API keys, billing accounts, and rate limits for every chain you support. When a provider drops free-tier access or changes terms without warning, your app breaks.

Blockscout PRO API eliminates that fragmentation. One account, one API key, dozens of mainnets and testnets — with the same endpoint structure you already know.

## Why Developers Switch to Blockscout PRO API

### Multichain by Default

Access onchain data across all Blockscout-supported chains through a single API key. Add a new chain by changing a `chain_id` parameter — no new vendor setup, no duplicated integration work.

```text theme={null}
https://api.blockscout.com/v2/api?chain_id=1&module=account&action=balance&address=0x...&apikey=proapi_xxx
```

Swap `chain_id=1` for `chain_id=8453` (Base), `chain_id=10` (Optimism), `chain_id=534352` (Scroll), or any supported chain.

### What Chains are Supported?

The latest list is also available at [dev.blockscout.com](http://dev.blockscout.com) under supported chains.

export const SupportedChains = () => {
  const [chains, setChains] = useState(null);
  const [error, setError] = useState(null);
  const [loaded, setLoaded] = useState(false);
  const load = async () => {
    if (loaded) return;
    setLoaded(true);
    try {
      const configRes = await fetch('https://raw.githubusercontent.com/blockscout/backend-configs/main/pro-api/prod/chains-config.json');
      const config = await configRes.json();
      const chainIds = Object.keys(config);
      const metaRes = await fetch(`https://chains.blockscout.com/api/chains?chain_ids=${chainIds.join(',')}`);
      const meta = await metaRes.json();
      const rows = chainIds.map(id => ({
        id,
        name: meta[id]?.name || id,
        isTestnet: meta[id]?.isTestnet ?? false
      })).sort((a, b) => a.name.localeCompare(b.name));
      setChains(rows);
    } catch (err) {
      setError(err);
    }
  };
  return <div onClick={load}>
      {!loaded && <p>Click to load the current list of supported chains…</p>}
      {loaded && error && <p>
          Couldn't load the live chain list — see the{' '}
          <a href="https://github.com/blockscout/backend-configs/blob/main/pro-api/prod/chains-config.json">
            current config
          </a>{' '}
          instead.
        </p>}
      {loaded && !error && !chains && <p>Loading supported chains…</p>}
      {chains && <>
          <h4>Mainnets</h4>
          <table>
            <thead>
              <tr><th>Chain</th><th>Chain ID</th></tr>
            </thead>
            <tbody>
              {chains.filter(c => !c.isTestnet).map(c => <tr key={c.id}><td>{c.name}</td><td>{c.id}</td></tr>)}
            </tbody>
          </table>
          <h4>Testnets</h4>
          <table>
            <thead>
              <tr><th>Chain</th><th>Chain ID</th></tr>
            </thead>
            <tbody>
              {chains.filter(c => c.isTestnet).map(c => <tr key={c.id}><td>{c.name}</td><td>{c.id}</td></tr>)}
            </tbody>
          </table>
        </>}
    </div>;
};

<Accordion title="PRO API Supported Chains">
  <SupportedChains />
</Accordion>

### Etherscan-Compatible Endpoints

Already using Etherscan V2's unified API? Migration is trivial — the structure is nearly identical. Etherscan uses `api.etherscan.io/v2/api?chainid=`, Blockscout uses `api.blockscout.com/v2/api?chain_id=`. Same modules, same parameters — swap the base URL and key.

**→ [Migration Guide: Etherscan to Blockscout](/devs/migrate-from-etherscan)**

<Info>
  All PRO API endpoints are documented individually in the API Reference menu
</Info>

### More Capacity at Every Tier

|                | Blockscout PRO API                    | Etherscan              |
| -------------- | ------------------------------------- | ---------------------- |
| **Free**       | 100K credits/day · 5 RPS · All chains | 3 RPS · Limited chains |
| **\$49/mo**    | 100M credits · 15 RPS                 | 100K calls · 5 RPS     |
| **\$199/mo**   | 500M credits · 30 RPS                 | 200K calls · 10 RPS    |
| **Enterprise** | Custom                                | Custom                 |

### Explorer-Enriched Data

PRO API serves the same indexed, decoded, and structured data that powers Blockscout explorers. That means token metadata, proxy implementations, internal transactions, and contract context — not just raw RPC responses.

## Built For

* **Dapps & Wallets** — Transaction history, token balances, NFTs, and contract activity across chains
* **AI Agents & Bots** — Structured onchain data for monitoring, automation, and AI-driven workflows
* **Analytics & Research** — Cross-chain behavior analysis, dashboards, and reporting
* **Operational Tooling** — Debugging, compliance workflows, and internal monitoring

## Get Started in 3 Steps

1. **Create an account** at [dev.blockscout.com](https://dev.blockscout.com)
2. **Generate your API key** — free tier starts immediately
3. **Query any supported chain** using familiar REST or JSON-RPC endpoints

No credit card required for the free tier. Upgrade when you're ready.

**→ [Start Building](https://dev.blockscout.com)**

## Trusted Infrastructure

Blockscout powers explorers for 100+ L2s and scaling projects. The PRO API runs on the same infrastructure and data pipeline — formalized for production workloads with higher limits, real-time usage dashboards, and up to 50 API keys per account.

**→ [View Supported Chains](https://chains.blockscout.com)** **→ [API Documentation](https://docs.blockscout.com/devs/apis)** **→ [Developer Portal](https://dev.blockscout.com)**