Pay for one Bitcoin answer.

This is the shortest path from zero setup to a paid Satoshi API response: Discover the endpoint, receive a 402 challenge, resend with PAYMENT-SIGNATURE, and read the JSON.

/api/v1 is the canonical stable API path. Versionless aliases exist for a few hero endpoints, but production integrations should keep canonical /api/v1 URLs unless you have a reason to use the shorter form.

Golden path

1. Discover paid endpoints

curl https://bitcoinsapi.com/.well-known/x402
curl https://bitcoinsapi.com/openapi.json

2. Call a paid endpoint without payment

curl -i https://bitcoinsapi.com/api/v1/fees/landscape

You should receive HTTP 402 with a PAYMENT-REQUIRED challenge. That is the quote your x402 client signs.

3. Resend with payment

curl -i https://bitcoinsapi.com/api/v1/fees/landscape \
  -H "PAYMENT-SIGNATURE: <signed-x402-payment>"

A valid payment returns HTTP 200 plus PAYMENT-RESPONSE and the normal Satoshi API JSON envelope.

Use-case first endpoints

Need	Canonical endpoint	Short alias
Should I send now or wait?	`/api/v1/fees/landscape`	`/fees/landscape`
What would the next block look like?	`/api/v1/mining/nextblock`	`/mining/nextblock`
Explain fee conditions in plain English	`/api/v1/ai/fees/advice`	`/ai/fees/advice`
Compare fee estimators	`/api/v1/fees/observatory/scoreboard`	`/fees/observatory/scoreboard`
Explain a transaction	`/api/v1/ai/explain/transaction/{txid}`	`/ai/explain/transaction/{txid}`

When you do not want x402

Use an API key. API-key authentication is checked before x402 payment requirements, so registered keys can call included endpoints directly through their tier limits.

curl https://bitcoinsapi.com/api/v1/register \
  -H "Content-Type: application/json" \
  -d '{"email":"agent@example.com","agreed_to_terms":true}'

For complete endpoint reference, use /docs. For machine-readable agent context, use /llms.txt and /llms-full.txt.