The core API covers on-chain data: blocks, transactions, addresses, accounts, assets, epochs, stake pools, IPFS, Bitcoin, and Midnight. Add-ons unlock additional capability surfaces, and WebSocket packages add real-time streaming.
Add-ons
| Add-on | Unlocks |
|---|
| Market Data | Prices, OHLCV candles, DEX pools/orders/quotes/swaps, NFT stats, blueprints, leaderboard |
| Wallet Analytics | Holdings, value history, and FIFO-based P&L per wallet |
| Transaction Builder | Server-side UTXO selection and unsigned CBOR for transfers, staking, governance, and DEX swaps |
| MCP Server | Model Context Protocol endpoint to connect Claude and other AI agents to Nexus data and tools |
WebSocket packages
Real-time streaming is offered separately from add-ons. See WebSocket Streaming.
| 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.
Enterprise includes everything. The Enterprise plan bundles all add-ons and WebSocket Unlimited, with no separate setup.
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:
{
"error": "payment_required",
"addon": "marketData",
"message": "This endpoint requires the marketData add-on."
}
addon field tells you which add-on to enable. WebSocket access is enforced at connection time instead (see WebSocket Streaming). 