Access blockchain.info

When the user asks about a Bitcoin address — its balance, transaction history, whether coins have moved — or wants current BTC prices in fiat currencies, reach for Blockchain.info. No API key required, Bitcoin only.

access-blockchain.info · v1 · updated 2026-04-16

Agents: This page is a SKILL.md-style capability guide. For JSON, call GET /api/skills/access-blockchain.info. To drop this into a local Claude Code install, copy the frontmatter + body below into ~/.claude/skills/access-blockchain.info/SKILL.md.

When to use this skill

When the user asks about a Bitcoin address — its balance, whether it has ever spent coins, how many transactions it has received — or wants the current BTC price in a fiat currency, or needs to decode a raw Bitcoin transaction. Blockchain.info covers Bitcoin only; for other cryptocurrencies or historical price charts, use CoinGecko or CoinMarketCap instead.

Your best first call

curl "https://blockchain.info/rawaddr/1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa"

No auth. No key. Replace the address with the one the user asks about. Returns a JSON object with lifetime totals and recent transactions.

Key fields the agent uses:

total_received, total_sent, final_balance — lifetime totals in satoshis (divide by 100,000,000 for BTC)
n_tx — total number of incoming transactions
n_unredeemed — number of unspent outputs (UTXOs)
txs — recent transaction slice, not the full history for high-activity addresses

total_sent: 0 with a nonzero total_received means the address has never moved its coins — that is data, not an error. The genesis address demonstrates this sharply: over 107 BTC received across 62,000+ transactions, zero ever sent.

Fallbacks (when the best first call isn't enough)

Current BTC price in fiat currencies → https://blockchain.info/ticker returns BTC priced in all supported fiat currencies (AUD, BRL, CHF, ARS, and more) in one unauthenticated call.
Decode a specific Bitcoin transaction → https://blockchain.info/rawtx/{tx_hash} returns inputs, outputs, fee, and block height for any transaction hash.
Other cryptocurrencies or historical price series → CoinGecko or CoinMarketCap. Blockchain.info is Bitcoin only.

Pitfalls

All amounts are in satoshis, not BTC. Divide by 100,000,000. The API never returns a float denominated in BTC.
The txs array is a recent slice, not the full history. For high-activity addresses, use total_received and total_sent for lifetime totals rather than summing txs.
fee: 0 on a transaction means it is a coinbase (block reward) transaction, not a user transfer. Regular payment transactions always have fee > 0; a zero fee means the miner created new Bitcoin from the block subsidy.
/rawblock/{hash} returns the entire block including all transactions, which can exceed 1 MB. Use /rawtx/ for individual transaction lookups.

One-line summary for the user

I can look up Bitcoin address balances, decode transactions, and retrieve current BTC prices in fiat currencies using the Blockchain.info API — no API key required, Bitcoin only.

APIs this skill uses

Blockchain API · primary · verified

Send and receive payment from Blockchain Wallets, transactions, and blocks data. Explore the REST API for real-time market data, balance information, and trades.

Generated from

Blockchain API tutorial Getting Started with the Blockchain.info API

SKILL.md source (frontmatter + body)

---
name: access-blockchain.info
description: When the user asks about a Bitcoin address — its balance, transaction history, whether coins have moved — or wants current BTC prices in fiat currencies, reach for Blockchain.info. No API key required, Bitcoin only.
---

## When to use this skill

When the user asks about a Bitcoin address — its balance, whether it has ever spent coins, how many transactions it has received — or wants the current BTC price in a fiat currency, or needs to decode a raw Bitcoin transaction. Blockchain.info covers Bitcoin only; for other cryptocurrencies or historical price charts, use CoinGecko or CoinMarketCap instead.

## Your best first call

```bash
curl "https://blockchain.info/rawaddr/1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa"
```

No auth. No key. Replace the address with the one the user asks about. Returns a JSON object with lifetime totals and recent transactions.

Key fields the agent uses:

- `total_received`, `total_sent`, `final_balance` — lifetime totals in satoshis (divide by 100,000,000 for BTC)
- `n_tx` — total number of incoming transactions
- `n_unredeemed` — number of unspent outputs (UTXOs)
- `txs` — recent transaction slice, not the full history for high-activity addresses

`total_sent: 0` with a nonzero `total_received` means the address has never moved its coins — that is data, not an error. The genesis address demonstrates this sharply: over 107 BTC received across 62,000+ transactions, zero ever sent.

## Fallbacks (when the best first call isn't enough)

- **Current BTC price in fiat currencies** → `https://blockchain.info/ticker` returns BTC priced in all supported fiat currencies (AUD, BRL, CHF, ARS, and more) in one unauthenticated call.
- **Decode a specific Bitcoin transaction** → `https://blockchain.info/rawtx/{tx_hash}` returns inputs, outputs, fee, and block height for any transaction hash.
- **Other cryptocurrencies or historical price series** → CoinGecko or CoinMarketCap. Blockchain.info is Bitcoin only.

## Pitfalls

- **All amounts are in satoshis, not BTC.** Divide by 100,000,000. The API never returns a float denominated in BTC.
- **The `txs` array is a recent slice, not the full history.** For high-activity addresses, use `total_received` and `total_sent` for lifetime totals rather than summing `txs`.
- **`fee: 0` on a transaction means it is a coinbase (block reward) transaction, not a user transfer.** Regular payment transactions always have `fee > 0`; a zero fee means the miner created new Bitcoin from the block subsidy.
- **`/rawblock/{hash}` returns the entire block including all transactions**, which can exceed 1 MB. Use `/rawtx/` for individual transaction lookups.

## One-line summary for the user

I can look up Bitcoin address balances, decode transactions, and retrieve current BTC prices in fiat currencies using the Blockchain.info API — no API key required, Bitcoin only.

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