Whale Alert API

What Whale Alert API MCP server does

The Whale Alert API MCP server exposes a single MCP operation for finding high-value blockchain transfers. It covers Ethereum and Base, and returns recent transactions that meet a configurable minimum value in ETH. Results include the sender and recipient addresses, the transfer amount in ETH, an estimated USD value at the transfer time, the transaction hash, block number, and timestamp.

The returned transaction list is ordered from highest value to lowest value. This makes the service suitable for reviewing large movements, identifying potential market-moving activity, and examining smart-money flows. It is not intended for wallet balances, token pricing, or holder-distribution analysis; the README points to separate tools for those use cases.

How it works

The MCP endpoint is hosted at https://whale-alert.api.klymax402.com/mcp. An MCP client connects to that URL and invokes crypto_track_whale_transactions. The operation maps to a POST request at /api/whales when accessed over HTTP.

Each call is priced at $0.008. Payment uses the x402 protocol on Base L2 (eip155:8453) with USDC. An x402-aware client handles the payment-required response, signs the payment, and retries the request. The documented payment flow does not use an API key, account signup, or a conventional rate-limit quota.

Use the Whale Alert API MCP server when an agent needs a filtered view of large Ethereum or Base transfers rather than a general blockchain query interface. The minimum threshold is expressed in ETH, including when the selected chain is Base.

Setup and configuration

Add the hosted MCP URL to a compatible client configuration. The README specifically shows Claude Desktop and Cursor, and also mentions ElizaOS. A minimal configuration uses the whale-alert server name and the hosted /mcp URL; no environment variable or API key is documented.

For direct HTTP access, send a POST request to https://whale-alert.api.klymax402.com/api/whales with a JSON body. An empty body produces an x402 payment challenge rather than an immediately usable result, so the client must support the x402 payment cycle or provide an equivalent payment flow.

Tools and capabilities

crypto_track_whale_transactions accepts two optional parameters:

• chain: ethereum or base; defaults to ethereum.
• minValue: minimum transaction value in ETH; defaults to 100.

The response contains a transactions array, the selected chain, the applied minValue, and totalFound. Each transaction can contain from, to, valueEth, valueUsd, txHash, blockNumber, and timestamp fields. Transaction hashes can be used for on-chain verification.

Limitations and notes

The documented scope is limited to Ethereum and Base, with one whale-transaction tracking tool. The service reports estimated USD values rather than presenting them as a separate live price feed. It also does not provide wallet balances, token prices, or holder-distribution data.

The Whale Alert API MCP server requires a payment for each call, and the documented payment asset is USDC on Base. The README identifies Coinbase CDP as the primary facilitator and PayAI as a fallback. No local package installation command or self-hosting procedure is provided; the supported setup shown is the hosted MCP endpoint.