# chainquery joinpsbts — Bitcoin Core PSBT Combiner

> chainquery joinpsbts — Bitcoin Core PSBT Combiner 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).

Joins multiple distinct Partially Signed Bitcoin Transactions (PSBTs) into a single combined PSBT using Bitcoin Core's joinpsbts RPC, served pay-per-call over x402.

## Facts

- Endpoint: GET https://x402.chainquery.com/v1/rpc/joinpsbts
- 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/chainquery-joinpsbts-bitcoin-core-psbt-combiner-b43fcff9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_X-pInLLcvMR7AQd1bpSrg

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 chainquery-joinpsbts-bitcoin-core-psbt-combiner-b43fcff9
```

Example prompt: Combine these two PSBTs into a single PSBT using the Bitcoin Core joinpsbts RPC: 'cHNidP8BAH...' and 'cHNidP8BAF...'

## When to prefer this

Use this endpoint when you need to combine multiple distinct PSBTs into a single PSBT without requiring an API key, paying only per call via x402. Ideal for CoinJoin workflows, multisig coordination, or any scenario where separate parties contribute PSBTs that must be merged before signing and broadcasting.

## Known failure modes

- Invalid or malformed PSBT base64 strings cause RPC error
- PSBTs with conflicting inputs or overlapping UTXOs will be rejected
- Missing required 'params' query parameter with PSBT array returns error
- Payment failure over x402 protocol blocks access
- Malformed JSON in params query parameter causes parse error

## How this service works

chainquery Bitcoin RPC: pay-per-call Bitcoin Core over x402, no API key. Join multiple distinct PSBTs into a single PSBT. Bitcoin Core joinpsbts.

## Output

Returns a base64-encoded PSBT string that is the result of joining all input PSBTs into one combined transaction, as returned by Bitcoin Core's joinpsbts RPC method.

## 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": "joinpsbts result"
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/chainquery-joinpsbts-bitcoin-core-psbt-combiner-b43fcff9/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)