# Satoshi API - Bitcoin Fee Observatory Estimates

> Satoshi API - Bitcoin Fee Observatory Estimates is a paid API for AI agents from bitcoinsapi.com, paid per call via x402, $0.005/call, status down (last checked 2026-09-16).

Returns live Bitcoin fee recommendations, mempool context, and transaction cost estimates to help apps and agents decide when to send BTC

## Facts

- Endpoint: POST https://bitcoinsapi.com/api/v1/fees/observatory/estimates
- Price: $0.005/call
- Payment: x402
- Status: down
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/satoshi-api-bitcoin-fee-observatory-estimates-477276f1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__dkSecoe5HIRxHarrXK4N

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability satoshi-api-bitcoin-fee-observatory-estimates-477276f1 -d '<json body>'
```

Example prompt: What's the current Bitcoin fee recommendation — should I send my transaction now or wait, and what sat/vbyte rate should I use for a fast confirmation?

## When to prefer this

Choose this endpoint when an AI agent or app needs real-time Bitcoin fee intelligence — specifically when building Bitcoin wallets, payment processors, or automation bots that need to decide the optimal sat/vbyte rate or whether to delay a transaction. Prefer this over generic blockchain explorers when you need structured, AI-agent-friendly fee recommendations rather than raw mempool data.

## Known failure modes

- Network timeout if mempool data provider is slow or unavailable
- Returns ok:false if the fee data cannot be fetched
- Invalid or malformed input properties may result in a 400 error
- Rate limiting if called too frequently without payment
- Stale data if mempool snapshot is momentarily delayed

## How this service works

Know when to send Bitcoin and when to wait. Satoshi API gives apps and AI agents live fee recommendations, mempool context, and cost estimates. Free, open source.

## Output

A JSON object with a boolean 'ok' status and a 'source' identifier, along with live fee rate estimates (sat/vbyte) for different priority tiers (e.g. fast, standard, slow), mempool congestion context, and estimated transaction cost — helping the caller decide when and at what fee to broadcast a Bitcoin transaction.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "schema": {
  "type": "object",
  "properties": {
   "ok": {
    "type": "boolean"
   },
   "source": {
    "type": "string"
   }
  }
 },
 "example": {
  "ok": true,
  "source": "satoshi-api"
 },
 "mimeType": "application/json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/satoshi-api-bitcoin-fee-observatory-estimates-477276f1/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from bitcoinsapi.com](https://www.zero.xyz/host/bitcoinsapi.com/llms.txt)