# FastPath Bitcoin Transaction Lookup (Ethereum-style RPC)

> FastPath Bitcoin Transaction Lookup (Ethereum-style RPC) is a paid API for AI agents from api.nativebtc.org, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Fetches Bitcoin transaction details — fee, vsize, and fee rate — via a REST endpoint styled for Ethereum JSON-RPC consumers.

## Facts

- Endpoint: GET https://api.nativebtc.org/v1/tx/%7Btxid%7D
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastpath-bitcoin-transaction-lookup-ethereum-style-rpc-e02521b3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Un5qHeFTcu04y3K7uS54t

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-bitcoin-transaction-lookup-ethereum-style-rpc-e02521b3
```

Example prompt: Can you pull up the fee details for Bitcoin transaction 81c97a6c5b98a1019095de132727cda868694fb5d92534ebb07e475619e38325 — I want to see the fee in satoshis, the vsize, and the fee rate in sat/vb?

## When to prefer this

Choose this endpoint when you need fast, structured Bitcoin transaction fee and size data via a familiar REST/JSON interface, especially if your tooling is already oriented around Ethereum-style JSON-RPC conventions. Ideal for fee analysis, vsize inspection, and quick transaction lookups without running your own Bitcoin node.

## Known failure modes

- Invalid or malformed txid returns an error or success:false
- Transaction not found in the node's index returns a not-found error
- Network timeout or upstream Bitcoin node unavailability causes request failure
- Payment not processed (x402 payment required) results in 402 response

## 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

Returns a JSON object with the transaction's fee in satoshis, txid, virtual size in vbytes, fee rate in sat/vb, and a boolean success flag.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "fee": 220,
  "txid": "81c97a6c5b98a1019095de132727cda868694fb5d92534ebb07e475619e38325",
  "vsize": 110,
  "success": true,
  "feeRateSatVb": 2
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastpath-bitcoin-transaction-lookup-ethereum-style-rpc-e02521b3/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)