Mempool

Overview

Mempool.space provides a free, open Bitcoin API — mempool stats, blocks, transactions, fee estimates, and addresses — no key required (verified live). It’s the data behind the popular Mempool Explorer.

Quick Start

Current block height (verified live):

curl "https://mempool.space/api/blocks/tip/height"

900123

Fee estimates:

curl "https://mempool.space/api/v1/fees/recommended"

{ "fastestFee": 12, "halfHourFee": 9, "hourFee": 6, "economyFee": 3, "minimumFee": 1 }

Latest blocks / a transaction:

curl "https://mempool.space/api/blocks"
curl "https://mempool.space/api/tx/{txid}"

Address info:

curl "https://mempool.space/api/address/{address}"

Authentication

None — keyless (the public instance is free; run your own instance if you need more).

Rate Limits & Notes

• Free public instance; heavy use should self-host (the project is open-source).
• Endpoints: /api/blocks, /api/blocks/tip/height, /api/v1/fees/recommended, /api/tx/{id}, /api/address/{addr}, /api/mempool…
• Fee recommendations are in sat/vB — useful for wallet UIs.
• A self-hosted instance (mempool.space Docker stack) removes rate limits.

FAQ

Is Mempool free? Yes — the public API is free and keyless.

How do I get fee estimates? /api/v1/fees/recommended returns sat/vB rates.

What if I need more than the public limits? Self-host the open-source stack.