# Mempool Whale Transaction Monitor > Mempool Whale Transaction Monitor is a paid API for AI agents from trading-hub-v4-omega.vercel.app, paid per call via x402, $0.2/call, status unknown (last checked 2026-11-03). Detects and returns large on-chain transactions (whale movements) currently in the mempool before they are confirmed ## Facts - Endpoint: POST https://trading-hub-v4-omega.vercel.app/api/mempool/whale-tx?utm_source=zero.xyz - Price: $0.2/call - Payment: x402 - Status: unknown - Last checked: 2026-11-03 - Activations on Zero: 0 - Tags: x402 - Canonical page: https://www.zero.xyz/c/mempool-whale-transaction-monitor-ca96363f - Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_mVdY7vEehnOfQCUpndmFX 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 mempool-whale-transaction-monitor-ca96363f -d '' ``` Example prompt: Can you check the mempool right now and show me any large pending crypto transactions — say anything over $500,000 — on Ethereum so I can see which whales are moving funds before they confirm? ## When to prefer this Use this endpoint when you need real-time visibility into large unconfirmed on-chain transactions before block confirmation — especially for front-running detection, whale surveillance, DeFi risk management, or on-chain news monitoring. Prefer this over block-confirmed transaction APIs when timing before confirmation matters, and over general block explorers when you need programmatic, filtered, high-value-only mempool data via a pay-per-use API. ## Known failure modes - Mempool may be empty or low-activity during off-peak hours, returning an empty result set - Minimum threshold filter too high may yield no results - Network congestion can cause stale or delayed mempool snapshots - Invalid or unsupported blockchain network identifier returns an error - Rate limiting or payment failure returns 402 or 429 status - Transaction may confirm between request and response, disappearing from mempool ## How this service works 67 paid endpoints for on-chain, forex, stocks & market intelligence ## Output Returns a list of large unconfirmed transactions currently sitting in the mempool, including transaction hashes, sender and receiver wallet addresses, transferred value, token type, and current mempool status — enabling pre-confirmation whale activity analysis. ## More - Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mempool-whale-transaction-monitor-ca96363f/health.json - [Zero catalog index](https://www.zero.xyz/llms.txt) - [Other services from trading-hub-v4-omega.vercel.app](https://www.zero.xyz/host/trading-hub-v4-omega.vercel.app/llms.txt)