# Silverback Whale Movement Monitor

> Silverback Whale Movement Monitor is a paid API for AI agents from silverback-x402.onrender.com, paid per call via x402, $0.02/call, status down (last checked 2026-09-15).

Tracks large on-chain token transfers, buys, and sells above a USD threshold, returning a ranked list of whale moves with summary analytics

## Facts

- Endpoint: GET https://silverback-x402.onrender.com/api/v1/whale-moves
- Price: $0.02/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/silverback-x402-onrender-com-be767b34
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_xP5iIArUHooq2iFOI8P3n

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 silverback-x402-onrender-com-be767b34
```

Example prompt: Show me the top 10 whale moves for USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base chain with a minimum transaction size of $500,000 — I want to see who's buying, selling, and moving big amounts.

## When to prefer this

Use this endpoint when you need real-time whale activity intelligence for a specific ERC-20 token on Base (or other EVM chains), particularly when you want to identify large holders moving funds, detect buy/sell pressure from big wallets, or understand net flow dynamics. Prefer this over generic block explorers when you need structured, filterable, USD-denominated whale data with summary analytics in a single call.

## Known failure modes

- Invalid token contract address returns error or empty moves array
- Unsupported chain ID may return no results
- minValueUsd set too high may return zero moves
- limit exceeding 50 is clamped or rejected
- Payment failure via x402 returns 402 before data is served
- Rate limiting or cold start on Render free tier causes timeout

## How this service works

Monitor whale movements including buys, sells, and transfers for any token

## Output

Returns a list of up to 50 whale transactions including sender, receiver, move type (buy/sell/transfer), token symbol, raw value, USD value, transaction hash, block number, and timestamp. Also includes a summary with total move count, net flow, top buyers, top sellers, and the single largest move.

## Example request

```json
{
 "limit": 10,
 "token": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
 "chainId": 8453,
 "minValueUsd": 500000
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "limit": {
   "type": "number",
   "description": "Number of results (default: 10, max: 50)"
  },
  "token": {
   "type": "string",
   "description": "Token contract address (optional - ETH if not provided)"
  },
  "chainId": {
   "type": "number",
   "description": "Chain ID (default: 8453 for Base)"
  },
  "minValueUsd": {
   "type": "number",
   "description": "Minimum USD value to track (default: 100000)"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/silverback-x402-onrender-com-be767b34/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from silverback-x402.onrender.com](https://www.zero.xyz/host/silverback-x402.onrender.com/llms.txt)