Blockstream Esplora API
Keyless, no-signup REST API for full Bitcoin (and Liquid) chain data: blocks, transactions, addresses, UTXOs, mempool, and fee estimates.
Esplora is Blockstream's open-source Bitcoin block explorer, and its hosted public instance at blockstream.info exposes a clean RESTful HTTP API with zero authentication. You get block headers and full block data, raw and decoded transactions, address history and UTXO sets, mempool snapshots, and fee estimates. It is the go-to read API for Bitcoin agents that need fast chain reads without running bitcoind. The exact same API is self-hostable (the Esplora server is open source) if you outgrow the public instance or want privacy. A Liquid sidechain instance is also available at blockstream.info/liquid/api. Verified live June 2026.
Free tier
Free. The public hosted instance has no paid tier; self-host the open-source server for unlimited/private use. Blockstream also sells a dedicated enterprise Explorer API for high-volume needs.Rate limits
Not officially published. The public instance is best-effort and is known to return HTTP 429 (Too Many Requests) under aggressive use; throttle yourself or self-host the open-source Esplora server for volume.Auth
No keyBase URL
https://blockstream.info/apiWhat you'd build with it
- Look up Bitcoin address balances and full transaction history
- Build a Bitcoin payment/confirmation watcher in a Claude Skill
- Estimate Bitcoin network fees before broadcasting a tx
- Index UTXOs for a lightweight wallet backend
Key endpoints
- GET
/blocks/tip/heightCurrent best (tip) block height as plaintext - GET
/block/:hashBlock metadata (height, timestamp, tx count, merkle root) by hash - GET
/tx/:txidFull transaction detail including inputs, outputs and confirmation status - GET
/address/:addressAddress chain + mempool stats (funded/spent txo counts and sums, tx count) - GET
/address/:address/utxoList of unspent outputs for an address - GET
/fee-estimatesEstimated fee rate (sat/vB) per confirmation target
Members get the runnable recipe
Sign in free to copy the example request, see a sample response, and read the gotchas.