# FastPath API – Bitcoin UTXO Lookup by Address

> FastPath API – Bitcoin UTXO Lookup by Address is a paid API for AI agents from api.nativebtc.org, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Returns the unspent transaction outputs (UTXOs) for a given Bitcoin address, paid via x402 micropayment.

## Facts

- Endpoint: GET https://api.nativebtc.org/v1/utxos/%7Baddress%7D
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastpath-api-bitcoin-utxo-lookup-by-address-4ccbd7c5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_CP8sW3O2Ku6dXWwxkmkBH

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability fastpath-api-bitcoin-utxo-lookup-by-address-4ccbd7c5
```

Example prompt: Can you pull up all the unspent transaction outputs (UTXOs) for Bitcoin address bc1qexample... so I can see what's spendable there?

## When to prefer this

Choose this endpoint when you need the raw UTXO set for a specific Bitcoin address — especially useful for transaction construction, wallet balance checks, or UTXO-level auditing. It is particularly suited to Ethereum-tooling-familiar developers who want Bitcoin data in a familiar JSON-RPC-adjacent style. Use this over general blockchain explorers when you need structured, machine-readable UTXO data with micropayment access (x402) and no API key setup.

## Known failure modes

- Invalid or malformed Bitcoin address returns an error or empty UTXO list
- Address with no transaction history returns an empty UTXOs array
- Network or node connectivity issues may cause timeouts
- x402 payment failure or insufficient funds results in HTTP 402 and no data returned
- Rate limiting if too many requests are made in quick succession

## How this service works

FastPath translates Ethereum-style JSON-RPC requests into Bitcoin data, fee intelligence, mempool insight, and Core v31 package signals. Paid by x402.

## Output

A JSON object containing a list of UTXOs for the queried Bitcoin address, where each UTXO includes the transaction ID (txid), output index (vout), and value in satoshis. Also includes the queried address and a success flag.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "utxos": [
   {
    "txid": "81c97a6c5b98a1019095de132727cda868694fb5d92534ebb07e475619e38325",
    "vout": 0,
    "value": 125000
   }
  ],
  "address": "bc1qexample...",
  "success": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastpath-api-bitcoin-utxo-lookup-by-address-4ccbd7c5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.nativebtc.org](https://www.zero.xyz/host/api.nativebtc.org/llms.txt)