canonical: https://jentic.com/apis/nownodes.io/nownodes

# NOWNodes API

Jentic publishes the only available OpenAPI specification for NOWNodes API, keeping it validated and agent-ready. NOWNodes provides Blockchain-as-a-Service infrastructure with full-node RPC endpoints, BlockBook explorers, and WebSocket connections across 100+ chains including Bitcoin, Ethereum, Solana, Polygon, Arbitrum, Avalanche, and Cardano. The API exposes 12 endpoints covering JSON-RPC pass-through, BlockBook explorer queries, address and xpub lookups, UTXO retrieval, fee estimation, and transaction broadcast. It supports the operational tasks of reading blockchain state and submitting transactions without running and maintaining nodes.

## For AI agents

Read blockchain state and broadcast transactions across 100+ chains via JSON-RPC and BlockBook explorer endpoints, with single API-key access.

## Scope

Does not custody assets, sign transactions, or provide market price data - use for blockchain RPC reads, explorer queries, and signed transaction broadcast only.

## Capabilities

- Forward JSON-RPC calls to full nodes for Bitcoin, Ethereum, Solana, and 100+ other chains
- Query BlockBook explorers for blocks, transactions, and address details on UTXO chains
- Look up balances, balance history, and UTXOs for an address or xpub
- Estimate transaction fees for a given confirmation target
- Broadcast a signed transaction to the network
- Retrieve backend-specific transaction details for chain-aware logic

## Use cases

### Multi-Chain Wallet Backend

A wallet application reads balances and transaction history across many chains without operating its own node fleet. NOWNodes provides JSON-RPC and BlockBook explorer endpoints behind a single API key, and the network path variable selects the chain per request, so adding support for a new chain is configuration rather than infrastructure work.

Example prompt: Fetch the balance for a Bitcoin address via the BlockBook `/api/v2/address` endpoint and the balance for an Ethereum address via the eth network JSON-RPC

### Transaction Broadcasting and Fee Estimation

A wallet's send flow estimates the network fee for the desired confirmation target, then broadcasts the signed transaction. The `/api/v2/estimatefee/{confirmationTarget}` and `/api/v2/sendtx/{hex}` endpoints handle both steps, so the wallet does not need to maintain its own mempool and fee oracle.

Example prompt: Estimate the Bitcoin fee for a 6-block confirmation target and then broadcast a signed transaction hex via `/api/v2/sendtx`

### Block Explorer Backend

A custom block explorer app uses NOWNodes' BlockBook endpoints to render block, transaction, address, and xpub pages without running BlockBook directly. Endpoints like `/api/v2/block/{blockHashOrHeight}` and `/api/v2/tx/{txid}` return the structured data the explorer needs, while `/api/v2/balancehistory/{addressOrXpub}` powers historical charts.

Example prompt: Render an address page by calling `/api/v2/address/{address}` for the summary, `/api/v2/utxo/{addressOrXpub}` for unspent outputs, and `/api/v2/balancehistory` for the chart

### AI Agent Onchain Lookups

An AI agent answers user questions about onchain activity by calling NOWNodes through Jentic. The agent searches for the right RPC or BlockBook operation, loads the schema, and executes the call against the chain-specific subdomain rather than maintaining direct provider integrations.

Example prompt: Look up a transaction hash on Ethereum via JSON-RPC eth_getTransactionByHash and summarise the result for the user

## Key endpoints

| Method | Path | Description |
| --- | --- | --- |
| POST | `/` | Send a JSON-RPC request to the selected network |
| GET | `/api/v2/block/{blockHashOrHeight}` | Get a block by hash or height |
| GET | `/api/v2/tx/{txid}` | Get transaction details |
| GET | `/api/v2/address/{address}` | Get address details |
| GET | `/api/v2/utxo/{addressOrXpub}` | Get UTXOs for an address or xpub |
| GET | `/api/v2/sendtx/{hex}` | Broadcast a signed transaction |
| GET | `/api/v2/estimatefee/{confirmationTarget}` | Estimate the transaction fee |

## Key resources

- **JSON-RPC** — Forward JSON-RPC calls to full nodes for supported chains
- **BlockBook** — Block, transaction, address, xpub, UTXO, and fee endpoints across UTXO and EVM chains
- **Status** — Node and BlockBook health and status checks

## Why Jentic

- **Setup:** Wiring NOWNodes by hand means setting up its api-key header, selecting the right {network} host for each chain, and choosing between the JSON-RPC and BlockBook endpoints yourself on every call. Through Jentic you install once, import the NOWNodes API from the API Directory, store the key once, and your agent calls it.
- **Permission scoping:** NOWNodes selects the chain through a host server variable and takes lookup targets in the path or RPC body rather than a fixed resource id you can pin, so scope the agent to the operations it needs, such as reading a block or an address. You choose that set, so broadcasting a signed transaction via `/api/v2/sendtx/{hex}` is not included unless you add it.
- **Credential handling:** Your NOWNodes api-key is stored once, encrypted, by your own Jentic One instance and injected at execution time as the header. It never enters the agent's prompt, logs, or context.
- **Discovery method:** Agents search Jentic by intent such as 'look up a Bitcoin address balance' or 'fetch a transaction', and Jentic returns the matching JSON-RPC or BlockBook operation with its input schema and the network server variable so the agent calls the right endpoint without browsing the reference docs.

## Related APIs

- **Alchemy API** — Alchemy provides EVM-focused node infrastructure with richer enhanced APIs.
- **QuickNode API** — QuickNode is another node-as-a-service provider with global endpoints.
- **Covalent (GoldRush) API** — Covalent indexes onchain data into REST endpoints; pair with NOWNodes for raw RPC needs.

## FAQ

### Why is there no official OpenAPI spec for NOWNodes API?

NOWNodes does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call NOWNodes API via structured tooling. It is validated against the live API and kept up to date. Get started with Jentic One, the self-hosted execution layer.

### What authentication does the NOWNodes API use?

NOWNodes uses an API key passed in the api-key header. Through Jentic, the key is held in the vault and injected at execution time, so the agent never sees the raw value in its context.

### Can I broadcast a signed transaction with the NOWNodes API?

Yes. GET `/api/v2/sendtx/{hex}` broadcasts a signed transaction hex to the chosen network's mempool. Pair it with `/api/v2/estimatefee/{confirmationTarget}` to set the right fee before signing.

### What are the rate limits for the NOWNodes API?

The OpenAPI spec does not declare explicit rate limits. NOWNodes applies plan-based limits in production; check the response headers and the NOWNodes dashboard for current limits and upgrade tiers.

### How do I query a specific blockchain through Jentic?

Search Jentic for 'look up address details on bitcoin'. Jentic returns the GET `/api/v2/address/{address}` operation with the network server variable, so the agent can target the right NOWNodes subdomain (for example btcbook.nownodes.io) for the chain in question.

### Which chains does the NOWNodes API support?

The OpenAPI spec lists supported networks via server variable enums covering BTC, ETH (and ETH archive), BSC, SOL, LTC, DOGE, MATIC, ARB, OP, AVAX, ADA, XRP, DOT, TRX, ATOM, XLM, ALGO, NEAR, FTM, CELO, ONE, KLAY, ZEC, DASH, BCH, ETC, and BNB, with BlockBook covering the UTXO subset.

### Can I limit what my agent is allowed to do with the NOWNodes API?

Yes. Because you run Jentic One yourself, your own rules decide which NOWNodes operations and credentials the agent may use. You can scope the agent to read-only calls such as fetching a block via GET `/api/v2/block/{blockHashOrHeight}` or an address via GET `/api/v2/address/{address}`, and JSON-RPC reads, while leaving out the ones you do not want. Broadcasting a signed transaction via GET `/api/v2/sendtx/{hex}` is only available to the agent if you explicitly include it.