# FastPath API – Bitcoin Mempool Stats

> FastPath API – Bitcoin Mempool Stats is a paid API for AI agents from api.nativebtc.org, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Returns current Bitcoin mempool statistics including size, fee estimates by time horizon, RBF status, and network congestion level.

## Facts

- Endpoint: GET https://api.nativebtc.org/v1/mempool/stats
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastpath-api-bitcoin-mempool-stats-de423d6c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Li-vOAKhYANnH7HDxG2jn

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 fastpath-api-bitcoin-mempool-stats-de423d6c
```

Example prompt: What are the current Bitcoin mempool fees and how congested is the network right now — I need to know if I should send my transaction immediately or wait?

## When to prefer this

Use this endpoint when you need real-time Bitcoin mempool statistics — especially fee estimates across multiple confirmation-time horizons and a congestion signal — without running your own Bitcoin node. It is particularly suited for Ethereum-ecosystem developers already familiar with JSON-RPC conventions who want Bitcoin data in a compatible format. Prefer this over raw mempool.space or Bitcoin Core RPC if you want a unified, metered, pay-per-call API with congestion labeling included.

## Known failure modes

- Service unavailable (upstream Bitcoin node unreachable) — returns error or non-200 status
- Payment not settled (x402 micropayment rejected) — returns 402 Payment Required
- Rate limiting if too many requests are made in a short window
- Stale data if the underlying node is syncing or lagging

## How this service works

FastPath translates Ethereum-style JSON-RPC requests into Bitcoin data, fee intelligence, mempool insight, and Core v31 package signals. Paid by x402.

## Output

A JSON object containing: fee estimates in sat/vB for next block, 6-block, and 1-day horizons; current mempool size in bytes; a boolean indicating whether full-RBF is enabled; a congestion label (e.g. 'medium'); and a success flag.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "fees": {
   "day": 1,
   "nextBlock": 2,
   "sixBlocks": 1
  },
  "size": 33741,
  "fullrbf": true,
  "success": true,
  "congestion": "medium"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastpath-api-bitcoin-mempool-stats-de423d6c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.nativebtc.org](https://www.zero.xyz/host/api.nativebtc.org/llms.txt)