# BTC Node API — Mempool Pending Transactions

> BTC Node API — Mempool Pending Transactions is a paid API for AI agents from api.relai.fi, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Returns the list of pending (unconfirmed) transactions currently in the Bitcoin mempool

## Facts

- Endpoint: GET https://api.relai.fi/relay/1780781322365/api/mempool
- 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/btc-node-api-mempool-pending-transactions-f8add7a0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_PVZdsUxTejwxhOq2H1t6b

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 btc-node-api-mempool-pending-transactions-f8add7a0
```

Example prompt: Can you pull the current list of pending unconfirmed Bitcoin transactions from the mempool right now?

## When to prefer this

Use this endpoint when you need real-time access to the Bitcoin mempool — specifically the set of unconfirmed transactions — for monitoring network congestion, fee estimation context, transaction tracking, or blockchain analytics. Prefer this over block-explorer scraping when you need a direct node-level view of pending transactions.

## Known failure modes

- Node connectivity issues may return 503 or empty response
- Rate limiting may return 429 if called too frequently
- Payment of 0.005 USDC required via x402 protocol; missing payment returns 402
- Bitcoin node may be syncing, returning stale or incomplete mempool data

## How this service works

Mempool pending transactions

## Output

A list or collection of pending Bitcoin transactions currently sitting in the mempool awaiting confirmation, likely including transaction IDs, fees, sizes, and other metadata about unconfirmed transactions on the Bitcoin network.

## Example request

```json
{
 "input": {
  "type": "http",
  "method": "GET",
  "queryParams": {}
 }
}
```

## 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"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/btc-node-api-mempool-pending-transactions-f8add7a0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.relai.fi](https://www.zero.xyz/host/api.relai.fi/llms.txt)