# Preflight Bitcoin Transaction Inspector

> Preflight Bitcoin Transaction Inspector is a paid API for AI agents from preflight402.com, paid per call via x402, $0.1/call, status unknown (last checked 2026-10-01).

Decodes a raw Bitcoin transaction hex or PSBT and returns inputs, outputs, script types, addresses, vsize, fee rate, RBF flags, dust outputs, non-standard sighash flags, and unsigned inputs — offline, no network access.

## Facts

- Endpoint: POST https://preflight402.com/v1/btc/tx-inspect?utm_source=zero.xyz
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/preflight-bitcoin-transaction-inspector-6e5c84f2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_LcgJFFOQT745QPNI8VtdC

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 preflight-bitcoin-transaction-inspector-6e5c84f2 -d '<json body>'
```

Example prompt: Before I sign this Bitcoin PSBT, can you inspect it for me and tell me all the inputs, outputs, addresses, fee rate, vsize, and flag anything unusual like RBF, dust outputs, or unsigned inputs? Here's the PSBT: cHNidP8BAH...

## When to prefer this

Use this endpoint when you need to inspect a Bitcoin transaction or PSBT offline, without any network access, before signing or broadcasting. Prefer this over chain-aware endpoints when you only want structural and objective signal analysis of the raw bytes (inputs, outputs, script types, RBF, dust, sighash flags) and do not need UTXO confirmations or mempool status. It is the right choice for automated signing pipelines, hardware wallet integrations, or any agent that must verify what it is about to sign.

## Known failure modes

- Invalid or malformed transaction hex returns a parse error
- Malformed PSBT base64 returns a decode error
- Fee rate cannot be returned when input values are missing from the PSBT (no UTXO data)
- Network mismatch (e.g., testnet address in mainnet mode) may cause address decoding issues
- Empty or missing both 'raw' and 'psbt' fields returns a validation error

## How this service works

Call before signing or broadcasting a Bitcoin transaction. Decodes a raw transaction hex or a PSBT and returns inputs, outputs, script types, addresses, vsize, fee rate when derivable, and objective signals such as RBF, dust outputs, non-standard sighash flags and unsigned inputs. Parses only the bytes you send: no network access. Describes the transaction; never advises whether to sign it.

## Output

A structured breakdown of the decoded transaction including: all inputs (with script type, address, value if derivable, and signed/unsigned status), all outputs (with address, script type, value, and dust flag), overall vsize, fee rate when calculable, RBF flag, presence of non-standard sighash flags, and a list of any unsigned inputs. No network calls are made; all analysis is from the raw bytes provided.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "raw": {
   "type": "string"
  },
  "psbt": {
   "type": "string"
  },
  "network": {
   "enum": [
    "mainnet",
    "testnet"
   ],
   "type": "string",
   "default": "mainnet"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/preflight-bitcoin-transaction-inspector-6e5c84f2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from preflight402.com](https://www.zero.xyz/host/preflight402.com/llms.txt)