Mempool.space is a widely-used open-source block explorer and mempool visualizer. It provides a browser-based interface for exploring blocks, transactions, and addresses, and exposes an API for programmatic access to that data.
Satoshi API is a self-hosted REST API layer that connects directly to a Bitcoin Core node. It provides analyzed endpoints (fee recommendations in sat/vB, congestion scores, UTXO analysis), reorg-aware caching, and MCP integration for AI agents. It does not include a visual explorer.
The two tools occupy different niches. Choosing between them depends on whether the goal is visual exploration and address lookups, or building production applications on a private node.
Can You Use Both?
Yes — they complement each other.
A common pattern is to use Satoshi API as the backend for application logic (fee estimation, mempool monitoring, block analysis on your own node) while using Mempool.space for address lookups and visual debugging. Mempool.space covers address-indexed data that Bitcoin Core does not expose natively. Satoshi API covers analyzed, cached, privacy-preserving access to everything your node knows. There is no reason to choose only one.
Summary
Mempool.space is the best open-source block explorer available. It has a large community, a polished UI, and broad coverage including Lightning Network data and address lookups. For anyone who needs to visually explore the Bitcoin network or look up addresses without running a node, it is the clear choice.
Satoshi API targets a different use case: developers who already run Bitcoin Core and want a clean, analyzed REST API on top of it. It provides privacy (no third-party sees your queries), smart caching (reorg-aware, depth-based TTL), and MCP integration for the growing ecosystem of AI agents interacting with Bitcoin.
The right tool depends on the job. For many projects, using both is the best approach.