# mempool.space API

> mempool.space returns Bitcoin fee estimates, address balances, and recent transactions as a workflow and API.

mempool.space, also called Mempool, returns Bitcoin fee recommendations, estimated costs, and the Bitcoin price; it needs no input. Get bitcoin address returns address balances and recent transactions; it needs a Bitcoin address and optionally a transaction count.

- Page: https://fous.com/tools/mempool-space
- Handle: `@mempool-space`
- Category: [Blockchain](https://fous.com/tools/category/blockchain)
- Source website: https://mempool.space
- Last verified: Sep 29, 2026

## Methods

### Get bitcoin address

Operation `get_bitcoin_address`, version 1. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.

See a Bitcoin address’s confirmed and pending balances, lifetime received and sent amounts, and up to 50 recent transactions. USD balance uses the latest reported Bitcoin price; received and sent totals include pending transactions.

**Input**

| Field | Type | Required | Example | Description |
|---|---|---|---|---|
| `address` | string | yes | `"1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa"` | Bitcoin address starting with 1, 3 or bc1, for example 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa. |
| `max_transactions` | integer | no | `10` | Maximum recent transactions to return, for example 10. Defaults to 10; maximum 50. |

**Input schema**

```json
{
  "type": "object",
  "required": [
    "address"
  ],
  "properties": {
    "address": {
      "type": "string",
      "description": "Bitcoin address starting with 1, 3 or bc1, for example 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa.",
      "examples": [
        "1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa",
        "3J98t1WpEZ73CNmQviecrnyiWrnqRhWNLy",
        "1BYym9pkkPXM7He9QtdJQ93eGXTu462mdJ"
      ]
    },
    "max_transactions": {
      "type": "integer",
      "default": 10,
      "maximum": 50,
      "minimum": 1,
      "description": "Maximum recent transactions to return, for example 10. Defaults to 10; maximum 50.",
      "x-fous-developer": true,
      "examples": [
        10,
        50
      ]
    }
  },
  "additionalProperties": false,
  "examples": [
    {
      "address": "1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa",
      "max_transactions": 10
    },
    {
      "address": "3J98t1WpEZ73CNmQviecrnyiWrnqRhWNLy",
      "max_transactions": 50
    },
    {
      "address": "1BYym9pkkPXM7He9QtdJQ93eGXTu462mdJ"
    }
  ]
}
```

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `address` | string | `"1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa"` |  |
| `total_sent_btc` | number | `0` |  |
| `transaction_count` | integer | `66619` |  |
| `total_received_btc` | number | `57.47644956` |  |
| `recent_transactions` | array |  |  |
| `recent_transactions[].link` | string | `"https://mempool.space/tx/c99e446ab2d43e999de5708e62a8384f187f8015cc6d188af2a23e8d313b39a4"` | Transaction page on mempool.space. |
| `recent_transactions[].fee_btc` | number | `2e-7` | Whole transaction network fee in BTC, not necessarily paid by this address. |
| `recent_transactions[].confirmed` | string | `"no"` | Whether this transaction is confirmed. |
| `recent_transactions[].date_time` | string or null | `"2026-09-06T09:33:10+00:00"` | Confirmation date and time in UTC, or null when unconfirmed. |
| `recent_transactions[].block_height` | integer or null | `965743` | Block height, or null when unconfirmed. |
| `recent_transactions[].net_change_btc` | number | `0.00003672` | Change in this address’s balance in BTC, negative for a net send. |
| `recent_transactions[].transaction_id` | string | `"c99e446ab2d43e999de5708e62a8384f187f8015cc6d188af2a23e8d313b39a4"` | Transaction ID. |
| `confirmed_balance_btc` | number | `57.47633581` |  |
| `confirmed_balance_usd` | number | `4779042.37` |  |
| `unconfirmed_balance_btc` | number | `0.00011375` |  |

**Example input**

```json
{
  "address": "1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa",
  "max_transactions": 10
}
```

**Example output**

```json
{
  "address": "1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa",
  "total_sent_btc": 0,
  "transaction_count": 66619,
  "total_received_btc": 57.47644956,
  "recent_transactions": [
    {
      "link": "https://mempool.space/tx/c99e446ab2d43e999de5708e62a8384f187f8015cc6d188af2a23e8d313b39a4",
      "fee_btc": 2e-7,
      "confirmed": "no",
      "date_time": null,
      "block_height": null,
      "net_change_btc": 0.00003672,
      "transaction_id": "c99e446ab2d43e999de5708e62a8384f187f8015cc6d188af2a23e8d313b39a4"
    },
    {
      "link": "https://mempool.space/tx/4fe8b2b6fec09c158e1bd622e236a629510c87d4f77a9778f416a850aab041db",
      "fee_btc": 4.3e-7,
      "confirmed": "no",
      "date_time": null,
      "block_height": null,
      "net_change_btc": 0.00000546,
      "transaction_id": "4fe8b2b6fec09c158e1bd622e236a629510c87d4f77a9778f416a850aab041db"
    },
    {
      "link": "https://mempool.space/tx/5b38b8e6c131189d1366d8b73241a6034ccd637edd4d5ad1c7195dfb92d9e847",
      "fee_btc": 5.5e-7,
      "confirmed": "no",
      "date_time": null,
      "block_height": null,
      "net_change_btc": 0.00000546,
      "transaction_id": "5b38b8e6c131189d1366d8b73241a6034ccd637edd4d5ad1c7195dfb92d9e847"
    }
  ],
  "confirmed_balance_btc": 57.47633581,
  "confirmed_balance_usd": 4779042.37,
  "unconfirmed_balance_btc": 0.00011375
}
```

### Get bitcoin fees

Operation `get_bitcoin_fees`, version 1. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.

Get current Bitcoin fee-rate recommendations, estimated USD costs for a 140-vbyte transaction, and the Bitcoin price in USD. Confirmation times are estimates, not guarantees.

**Input**

No input.

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `reading_time` | string | `"2026-09-29T04:48:00Z"` | Time these readings were fetched, in UTC. |
| `currency_code` | string | `"USD"` | Currency of estimated costs and Bitcoin price (USD). |
| `economy_cost_usd` | number | `0.1164184` | Estimated USD fee for a 140-vbyte transaction at the economy rate. |
| `minimum_cost_usd` | number | `0.1164184` | Estimated USD fee for a 140-vbyte transaction at the minimum rate. |
| `bitcoin_price_usd` | number | `83156` | Price of one bitcoin in US dollars. |
| `one_hour_cost_usd` | number | `0.1164184` | Estimated USD fee for a 140-vbyte transaction at the about 1 hour rate. |
| `next_block_cost_usd` | number | `0.4656736` | Estimated USD fee for a 140-vbyte transaction at the next block (fastest) rate. |
| `thirty_minutes_cost_usd` | number | `0.4656736` | Estimated USD fee for a 140-vbyte transaction at the about 30 minutes rate. |
| `economy_fee_sat_per_vbyte` | number | `1` | Economy recommended transaction fee rate in satoshis per virtual byte. |
| `minimum_fee_sat_per_vbyte` | number | `1` | Minimum recommended transaction fee rate in satoshis per virtual byte. |
| `one_hour_fee_sat_per_vbyte` | number | `1` | About 1 hour recommended transaction fee rate in satoshis per virtual byte. |
| `next_block_fee_sat_per_vbyte` | number | `4` | Next block (fastest) recommended transaction fee rate in satoshis per virtual byte. |
| `thirty_minutes_fee_sat_per_vbyte` | number | `4` | About 30 minutes recommended transaction fee rate in satoshis per virtual byte. |

**Example input**

```json
{}
```

**Example output**

```json
{
  "reading_time": "2026-09-29T04:48:00Z",
  "currency_code": "USD",
  "economy_cost_usd": 0.1164184,
  "minimum_cost_usd": 0.1164184,
  "bitcoin_price_usd": 83156,
  "one_hour_cost_usd": 0.1164184,
  "next_block_cost_usd": 0.4656736,
  "thirty_minutes_cost_usd": 0.4656736,
  "economy_fee_sat_per_vbyte": 1,
  "minimum_fee_sat_per_vbyte": 1,
  "one_hour_fee_sat_per_vbyte": 1,
  "next_block_fee_sat_per_vbyte": 4,
  "thirty_minutes_fee_sat_per_vbyte": 4
}
```

## Quick start

Replace `YOUR_API_KEY` with a Fous API key. To create one, open Developers at the bottom of Fous Studio, turn on Developer mode, then go to API keys (https://app.fous.com/keys). Change the values in `input` to run the same tool on new data.

```bash
curl 'https://api.fous.com/v1/query' \
  --fail-with-body --silent --show-error --max-time 180 \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H 'Content-Type: application/json' \
  --data-raw '{
  "api": "@mempool-space",
  "visibility": "public",
  "operation": "get_bitcoin_address",
  "version": 1,
  "input": {
    "address": "1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa",
    "max_transactions": 10
  },
  "response": {
    "format": "json"
  }
}'
```

```python
# Save as fous.py and run with python3 fous.py. No packages needed.
import json
import urllib.error
import urllib.request

api_key = "YOUR_API_KEY"

body = json.loads("{\n  \"api\": \"@mempool-space\",\n  \"visibility\": \"public\",\n  \"operation\": \"get_bitcoin_address\",\n  \"version\": 1,\n  \"input\": {\n    \"address\": \"1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa\",\n    \"max_transactions\": 10\n  },\n  \"response\": {\n    \"format\": \"json\"\n  }\n}")
request = urllib.request.Request(
    "https://api.fous.com/v1/query",
    data=json.dumps(body).encode("utf-8"),
    headers={
        "Authorization": f"Bearer {api_key}",
        "Content-Type": "application/json",
    },
    method="POST",
)
try:
    with urllib.request.urlopen(request, timeout=180) as response:
        result = json.load(response)
except urllib.error.HTTPError as error:
    raise RuntimeError(f"HTTP {error.code}: {error.read().decode('utf-8', errors='replace')}") from error
if result.get("success") is False:
    raise RuntimeError(result.get("error", {}).get("message", "Request failed"))
print(json.dumps(result["data"]["output"], indent=2))
```

```typescript
// Save as fous.mts and run with npx tsx fous.mts.
const apiKey = "YOUR_API_KEY";

const response = await fetch("https://api.fous.com/v1/query", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  },
  signal: AbortSignal.timeout(180_000),
  body: JSON.stringify({
  "api": "@mempool-space",
  "visibility": "public",
  "operation": "get_bitcoin_address",
  "version": 1,
  "input": {
    "address": "1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa",
    "max_transactions": 10
  },
  "response": {
    "format": "json"
  }
}),
});
type ApiResult = { success: boolean; data?: { output: unknown }; error?: { message: string } };
const result: ApiResult = await response.json();
if (!response.ok || result.success === false) {
  throw new Error(result.error?.message ?? `HTTP ${response.status}`);
}
if (!result.data) throw new Error("Missing API response data");
console.log(result.data.output);
```

## Use from an AI assistant

Connect this tool to Claude Code, Claude Desktop, Cursor, VS Code, Codex and any MCP client as its own MCP server. Each method is a typed tool whose arguments are the method’s input.

- Server URL: `https://api.fous.com/mcp/tools/mempool-space`
- Authorization: `Authorization: Bearer <Fous API key>`

**Tools**

- `get_bitcoin_address`: Get bitcoin address. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.
- `get_bitcoin_fees`: Get bitcoin fees. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.
- `fous_get_run`: the result of a run that was still going, by its `request_id`. Free.

Claude Code:

```bash
claude mcp add --scope user --transport http fous-mempool-space https://api.fous.com/mcp/tools/mempool-space --header "Authorization: Bearer ${FOUS_API_KEY:?Set FOUS_API_KEY to your Fous API key}"
```

To give the assistant every tool, connect `https://api.fous.com/mcp`: it finds one with `fous_search_tools` and runs it with `fous_run_tool`. Setup for other clients: https://fous.com/llms-full.txt.

## Use cases

- Compare estimated Bitcoin transaction costs across confirmation speeds.
- Track confirmed and pending balances for a Bitcoin address.
- Review recent transactions and balance changes for an address.
- Monitor lifetime Bitcoin received and sent by an address.

## FAQ

### Can I run it with my own inputs?

Yes. Change the inputs in Studio and press Run, or send new inputs from your code, or ask a connected AI assistant.

### Can I call this mempool.space tool as an API?

Yes. Send a POST request to /v1/query with your Fous API key and the inputs, and get JSON back.

### How much does it cost?

Each completed run costs 1 credit. Failed runs without a completed receipt are free; completed work can remain charged if delivery is interrupted. With pay as you go, a credit costs 1¢. Monthly plans cost less per credit.

### Do I need a mempool.space account?

No. You only need a Fous account.

### How current is the data?

Fous gets the data from mempool.space when you run it. Some results are reused for up to 24 hours, and results that use your account or key are never reused. It was last verified on Sep 29, 2026.

### What are the recommended Bitcoin fee rates?

Get bitcoin fees returns recommended fee rates for economy, minimum, about one hour, about 30 minutes, and the next block.

### What is the balance of a Bitcoin address?

Get bitcoin address returns confirmed and unconfirmed balances, including the confirmed balance in USD.

### Which transactions were recently made by an address?

Get bitcoin address returns up to 50 recent transactions, including confirmation status and the address’s net balance change.

## Related

- [Etherscan API](https://fous.com/tools/etherscan.md): Etherscan shows current gas prices, estimated costs, wallet balances, displayed token holdings and newest confirmed transactions, plus transaction status and details; pending fees are unconfirmed.
- [Coinbase API](https://fous.com/tools/coinbase.md): Coinbase provides public cryptocurrency prices and market overviews, including changing spot, buy, and sell quotes and 24-hour statistics; unavailable page facts may be missing.
- [Binance API](https://fous.com/tools/binance.md): Binance provides latest prices and rolling 24-hour statistics for active spot pairs, historical spot candles for a selected date range or newest first (up to 1,000), and current aggregated bid and ask levels.
- [CoinMarketCap API](https://fous.com/tools/coinmarketcap.md): CoinMarketCap returns prices, rankings and current Fear and Greed readings; gainers and losers include up to 30 top-100 coins above $50,000 in 24-hour volume.
- [Kraken API](https://fous.com/tools/kraken.md): Live cryptocurrency market prices and trading statistics from Kraken.
- [CoinGecko API](https://fous.com/tools/coingecko.md): CoinGecko returns cryptocurrency prices and histories, sector rankings and details, and trending coins; non-USD historical values cover 365 days, histories 7–365 days, and today’s prices may change.
- [US Census Bureau API](https://fous.com/tools/us-census-bureau.md): US Census Bureau returns statistics from varying Census years, population estimates through July 1, and address geographies using Census vintages that may differ from representation.
- [Best Buy API](https://fous.com/tools/best-buy.md): Best Buy returns US electronics and appliance listings, prices, deals, specifications, images, reviews, and nearby store pickup and shipping details; prices and availability can change by location and before checkout.
- [All Blockchain tools](https://fous.com/tools/category/blockchain)