# BaseBuilder Trading Mempool Whale Transaction Monitor

> BaseBuilder Trading Mempool Whale Transaction Monitor is a paid API for AI agents from bb-trading-gold.vercel.app, paid per call via x402, $0.195024/call, status unknown (last checked 2026-09-15).

Detects and returns large whale transactions currently in the mempool before they are confirmed on-chain

## Facts

- Endpoint: POST https://bb-trading-gold.vercel.app/api/mempool/whale-tx
- Price: $0.195024/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/basebuilder-trading-mempool-whale-transaction-monitor-7a7df39d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_oAxkg5E3QXwAqeRjEQr1o

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 basebuilder-trading-mempool-whale-transaction-monitor-7a7df39d -d '<json body>'
```

Example prompt: Show me any whale transactions currently sitting in the mempool on Base — I'm looking for pending transfers over 100,000 USDC or equivalent so I can get ahead of big market moves.

## When to prefer this

Choose this endpoint when you need real-time visibility into large unconfirmed transactions on Base before they are included in a block — ideal for front-running detection, MEV analysis, whale sentiment gauging, or alerting workflows in DeFi trading bots.

## Known failure modes

- Mempool may be empty or have no transactions exceeding the whale threshold at time of query
- Network congestion could cause stale or incomplete mempool snapshots
- Invalid or unsupported token address returns empty result or error
- Request timeout if mempool is under heavy load
- Authentication or payment failure (HTTP 402) if USDC balance is insufficient

## How this service works

BaseBuilder Trading API hub - 20 paid endpoints

## Output

Returns a list of large pending transactions in the mempool, including transaction hashes, sender and receiver wallet addresses, token amounts, gas prices, and current mempool status for each whale-level transfer detected.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/basebuilder-trading-mempool-whale-transaction-monitor-7a7df39d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from bb-trading-gold.vercel.app](https://www.zero.xyz/host/bb-trading-gold.vercel.app/llms.txt)