# Blockchain.com Explorer — Mempool Size Chart

> Blockchain.com Explorer — Mempool Size Chart is a paid API for AI agents from api.blockchain.info, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).

Returns historical mempool size chart data for Bitcoin, with configurable timespan, rolling average, and output format

## Facts

- Endpoint: POST https://api.blockchain.info/explorer-gateway-kt/x402/charts/mempool-size?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/blockchain-com-explorer-mempool-size-chart-390f73bb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_s3QAWZgsatx2Y7gALR-6W

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 blockchain-com-explorer-mempool-size-chart-390f73bb -d '<json body>'
```

Example prompt: Pull the Bitcoin mempool size chart data from Blockchain.com for the past year with an 8-hour rolling average in JSON format so I can see how network congestion has been trending.

## When to prefer this

Use this endpoint when you need historical or recent Bitcoin mempool size data from Blockchain.com's official explorer, especially when you want configurable time windows, rolling averages, and the choice of JSON or CSV output. Prefer this over generic crypto data APIs when you specifically need mempool-centric congestion metrics sourced directly from Blockchain.com, and when paying per-call via x402 USDC micropayments is acceptable.

## Known failure modes

- Invalid timespan format returns 400 error
- Unsupported rollingAverage window may return 400 or empty data
- Payment not fulfilled returns 402 Payment Required
- Rate limiting may return 429 Too Many Requests
- Network or upstream outage returns 503 Service Unavailable

## How this service works

Paid AI-agent access to Blockchain.com Explorer API

## Output

A JSON object (or CSV) containing time-series data points of Bitcoin mempool size, each with a timestamp and value, plus optional metadata fields such as chart name, unit, description, and period. JSON format includes structured metadata and a values array; CSV format returns raw two-column timestamp/value rows.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "cors": {
   "type": "boolean",
   "default": false,
   "description": "Enable CORS headers"
  },
  "format": {
   "enum": [
    "json",
    "csv"
   ],
   "type": "string",
   "default": "json",
   "description": "Response format:\n- `json` — Returns structured JSON with metadata and values\n- `csv` — Returns raw CSV data with timestamp and value columns (no metadata)\n"
  },
  "sampled": {
   "type": "boolean",
   "default": true,
   "description": "Apply sampling to reduce data points"
  },
  "metadata": {
   "type": "boolean",
   "default": false,
   "description": "Include metadata in response"
  },
  "timespan": {
   "type": "string",
   "default": "1y",
   "example": "1y",
   "description": "Time period (e.g., \"24h\", \"7d\", \"1y\", \"3y\")"
  },
  "rollingAverage": {
   "type": "string",
   "default": "8h",
   "example": "8h",
   "description": "Rolling average window (e.g., \"8h\", \"24h\")"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "format": "application/json",
 "example": {
  "name": "Mempool Size",
  "unit": "Bytes",
  "period": "minute",
  "status": "ok",
  "values": [
   {
    "x": 1704067200,
    "y": 14823904
   },
   {
    "x": 1704068100,
    "y": 15490211
   }
  ],
  "description": "The aggregate size of transactions waiting to be confirmed."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/blockchain-com-explorer-mempool-size-chart-390f73bb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.blockchain.info](https://www.zero.xyz/host/api.blockchain.info/llms.txt)