# Bitcoin Core combinepsbt — Merge Multiple PSBTs

> Bitcoin Core combinepsbt — Merge Multiple PSBTs is a paid API for AI agents from x402.chainquery.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Merges multiple Partially Signed Bitcoin Transactions (PSBTs) for the same underlying transaction into a single combined PSBT

## Facts

- Endpoint: GET https://x402.chainquery.com/v1/rpc/combinepsbt
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/bitcoin-core-combinepsbt-merge-multiple-psbts-acee7ecc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_roJbmIpSoWBrgtE9EqKI3

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 bitcoin-core-combinepsbt-merge-multiple-psbts-acee7ecc
```

Example prompt: I have two PSBTs for the same Bitcoin multisig transaction — one signed by wallet A and one signed by wallet B — can you combine them into a single PSBT using Bitcoin Core's combinepsbt? Pass them as a JSON array: ["cHNidP8BA...", "cHNidP8BB..."]

## When to prefer this

Use this endpoint when you need to merge partial signatures from multiple signers (e.g. multisig wallets, hardware wallets, CoinJoin participants) into one PSBT without running your own Bitcoin Core node. Prefer this over joinpsbts, which is for combining PSBTs for different transactions rather than merging signatures for the same transaction.

## Known failure modes

- PSBTs do not correspond to the same underlying transaction — Bitcoin Core returns an error
- Invalid base64 PSBT encoding — parse error from Bitcoin Core
- Empty or single-element PSBT array — may return error or passthrough
- params query param is not valid JSON — 400 or RPC error
- Payment not completed over x402 — 402 payment required response
- Node unavailable — 503 or timeout

## How this service works

chainquery Bitcoin RPC: pay-per-call Bitcoin Core over x402, no API key. Merge multiple PSBTs for the same transaction into one. Bitcoin Core combinepsbt.

## Output

Returns the combined PSBT as a base64-encoded string with all partial signatures and inputs from the provided PSBTs merged into one, ready for further signing or finalization.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "params": {
       "type": "string",
       "description": "optional: JSON-encoded array of positional RPC params"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "result": {
       "description": "combinepsbt result"
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/bitcoin-core-combinepsbt-merge-multiple-psbts-acee7ecc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.chainquery.com](https://www.zero.xyz/host/x402.chainquery.com/llms.txt)