# BaseBuilder2 Mempool Whale Transaction Monitor

> BaseBuilder2 Mempool Whale Transaction Monitor is a paid API for AI agents from bbx-trading.vercel.app, paid per call via x402, $0.195024/call, status unknown (last checked 2026-09-14).

Detects and returns large whale transactions from the blockchain mempool in real time

## Facts

- Endpoint: POST https://bbx-trading.vercel.app/api/mempool/whale-tx
- Price: $0.195024/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/basebuilder2-mempool-whale-transaction-monitor-fe94c6b8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_AC_hxRyo-ZVRsjOYv44vq

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 basebuilder2-mempool-whale-transaction-monitor-fe94c6b8 -d '<json body>'
```

Example prompt: Show me all whale transactions currently sitting in the mempool that are over 500 ETH — I want to see who's sending, who's receiving, and the transaction hashes.

## When to prefer this

Choose this endpoint when you need real-time, pre-confirmation visibility into large crypto transactions — particularly for whale tracking, front-running analysis, MEV research, or market sentiment signals based on pending on-chain activity. Prefer it over block-confirmed transaction APIs when timing is critical and you need to act before a transaction settles.

## Known failure modes

- Mempool may be empty or low activity during off-peak hours, returning no results
- Network congestion can cause timeouts or stale data
- Invalid or unsupported chain parameter returns an error
- Threshold set too high may return zero transactions
- Service may have rate limits or payment failures at $0.195 per call

## How this service works

BaseBuilder Trading API hub - 20 paid endpoints

## Output

Returns a list of large pending transactions from the blockchain mempool, including transaction hashes, sender and receiver addresses, token symbols, transfer values, and timestamps, filtered to surface only whale-scale activity above the configured threshold.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/basebuilder2-mempool-whale-transaction-monitor-fe94c6b8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from bbx-trading.vercel.app](https://www.zero.xyz/host/bbx-trading.vercel.app/llms.txt)