BTC Whale Signal API • Live on Signet test network only

Track BTC whale activity in one call.

Query public Bitcoin on-chain data for notable large-output activity. ArkAPI samples the latest confirmed block plus recent mempool transactions and returns counts, volume, latest block context, and the top BTC transactions in a clean paid API response.

2 sats / call

GET /api/btc-whale-signal

mempool.space data

2 minute cache

What It Does

This endpoint uses public mempool.space Bitcoin data to spot large BTC outputs in the latest block and recent mempool sample. It is best read as whale activity intensity, not as a directional buy or sell recommendation.

Data source: mempool.space.

Returns a compact activity signal and confidence score
Returns notable and large-output BTC counts
Returns notable BTC volume and USD estimates when price data is available
Returns the latest block height, block hash, and top observed transactions
Lightweight GET endpoint with no request body

How To Read It

The useful distinction is between notable activity and truly large activity. Notable outputs start at 25 BTC; large outputs start at 100 BTC. The endpoint reports both so dashboards can show quiet, moderate, elevated, or high activity without pretending to know intent.

signal is ArkAPI's activity read for the current sample
large_tx_count counts observed outputs at or above 100 BTC
notable_volume_btc totals observed outputs at or above 25 BTC
top_transactions includes txid, source, status, value, fee, and block context
fetched_at shows when ArkAPI assembled the cached response

Example Request

curl -H "Authorization: Bearer ak_your_token" \
  "https://arkapi.dev/api/btc-whale-signal" | jq

Use a funded token from the Fund page. This endpoint is cached for 2 minutes to keep responses fast and avoid hammering the public data source.

Example Response

{
  "success": true,
  "data": {
    "asset": "BTC",
    "source": "mempool.space",
    "method": "latest-block large-output scan plus recent mempool sample",
    "signal": "moderate_whale_activity",
    "summary": "Detected 5 notable BTC transactions in the latest block/mempool sample, including 0 at or above 100 BTC.",
    "confidence_pct": 58,
    "price_usd": 77821,
    "large_threshold_btc": 100,
    "notable_threshold_btc": 25,
    "large_tx_count": 0,
    "notable_tx_count": 5,
    "notable_volume_btc": 180.34823929,
    "notable_volume_usd": 14034880.33,
    "largest_tx_btc": 70.34469464,
    "largest_tx_usd": 5474294.48,
    "latest_block_height": 950310,
    "confirmed_tx_sample_size": 100,
    "mempool_tx_sample_size": 10,
    "top_transactions": [
      {
        "txid": "5af341dd6bf33a8519f340b6aba80709f255b877158c1ca401931d88c731567a",
        "source": "latest_block",
        "status": "confirmed",
        "value_btc": 70.34469464,
        "value_usd": 5474294.48,
        "fee_sats": 2320,
        "block_height": 950310
      }
    ],
    "fetched_at": "2026-05-21T01:27:59Z"
  },
  "cost_sats": 2,
  "balance_remaining": 1498,
  "response_ms": 337,
  "endpoint": "/api/btc-whale-signal"
}

Good Uses

Agent prompts that need fast BTC whale activity context
Market dashboards that want a compact on-chain large-transaction signal
Lightweight automation that watches confirmed and mempool BTC movement
Cheap repeated polling workflows where a 2-minute cache is acceptable

For broader platform usage, see the main docs and the live catalog.