> ## Documentation Index
> Fetch the complete documentation index at: https://nexus.gerowallet.io/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Add-ons & Streaming

> Optional capabilities you can attach to a Nexus plan

The core API covers on-chain data: blocks, transactions, addresses, accounts, assets, epochs, stake pools, Bitcoin, and Midnight. **Add-ons** enable additional capability surfaces, and **WebSocket packages** add live streaming.

An add-on is a separate paid SKU. A key that is in scope for the chain and network you are calling still returns **HTTP 402** on an add-on endpoint until the matching add-on is active on its plan, so network scope and capability are two independent gates.

## Add-ons

| Add-on                                                 | Enables                                                                                        | Path prefixes gated                                                                                      |
| ------------------------------------------------------ | ---------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------- |
| [**Market Data**](/docs/addons/market-data)                 | Prices, OHLCV candles, DEX pools/orders/quotes/swaps, NFT stats, blueprints, leaderboard       | `/api/market`, `/api/prices`, `/api/dex`, `/api/nft`, `/api/blueprints`, `/api/sync`, `/api/leaderboard` |
| [**Wallet Analytics**](/docs/addons/wallet-analytics)       | Holdings, value history, and FIFO-based P\&L per wallet                                        | `/api/wallet`                                                                                            |
| [**Transaction Builder**](/docs/addons/transaction-builder) | Server-side UTXO selection and unsigned CBOR for transfers, staking, governance, and DEX swaps | `/api/tx/`, `/api/aggregator`                                                                            |
| [**MCP Server**](/docs/addons/mcp-server)                   | Model Context Protocol endpoint to connect Claude and other AI agents to Nexus data and tools  | `/mcp/`                                                                                                  |
| **IPFS**                                               | Gateway content resolve plus `stat`, `ls`, IPNS resolution, and per-key pinning                | `/api/ipfs`                                                                                              |

## WebSocket packages

Live streaming is offered separately from add-ons. See [WebSocket Streaming](/docs/addons/websockets).

| Package   | Concurrent connections | Messages / mo |
| --------- | ---------------------- | ------------- |
| Starter   | 2                      | 100,000       |
| Pro       | 10                     | 2,000,000     |
| Unlimited | Unlimited              | Unlimited     |

## Enabling add-ons

Add-ons and WebSocket packages are managed from your account. Changes apply immediately.

<Note>
  **Enterprise includes everything.** The Enterprise plan bundles all add-ons and WebSocket Unlimited, with no separate setup.
</Note>

## How access is enforced

When you call an endpoint that belongs to an add-on you haven't activated, Nexus returns **HTTP 402 Payment Required**:

```json theme={null}
{
  "error": "payment_required",
  "addon": "marketData",
  "message": "Upgrade required at https://nexus.gerowallet.io/dashboard/billing/"
}
```

The `addon` field tells you which add-on to enable. WebSocket access is enforced at connection time instead (see [WebSocket Streaming](/docs/addons/websockets)).