# Satoshi API - Bitcoin Fee Observatory Scoreboard

> Satoshi API - Bitcoin Fee Observatory Scoreboard 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 a ranked leaderboard of Bitcoin fee estimation sources by accuracy, showing which sources have the lowest mean absolute error in sat/vB predictions.

## Facts

- Endpoint: POST https://bitcoinsapi.com/api/v1/fees/observatory/scoreboard
- 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-scoreboard-b9226097
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZHTmawxj1UrPDyjtnmyqw

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-scoreboard-b9226097 -d '<json body>'
```

Example prompt: Show me the fee estimator accuracy scoreboard so I can see which Bitcoin fee sources are most reliable right now — I want to know their rankings and mean absolute errors.

## When to prefer this

Choose this endpoint when you need to objectively compare the accuracy of multiple Bitcoin fee estimation sources rather than just getting a fee recommendation. It is ideal for developers selecting a fee oracle for their application, auditing current fee source reliability, or verifying that a particular source is performing well before committing to a high-value transaction.

## Known failure modes

- Invalid request body returns 400 with schema validation error
- Payment not included or rejected returns 402 Payment Required
- Service unavailable or mempool data stale returns 503
- Empty array returned if no sources have been evaluated recently
- Rate limiting may apply if payment fails to process

## 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

An array of ranked fee estimation sources, each with a source name, integer rank, sample count used for evaluation, and mean absolute error in sat/vB (satoshis per virtual byte). Lower mean absolute error indicates more accurate fee predictions. The Satoshi API's own source appears in the list for comparison.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "schema": {
  "type": "array",
  "items": {
   "type": "object",
   "required": [
    "source",
    "rank"
   ],
   "properties": {
    "rank": {
     "type": "integer"
    },
    "source": {
     "type": "string"
    },
    "sampleCount": {
     "type": "integer"
    },
    "meanAbsoluteErrorSatVb": {
     "type": "number"
    }
   }
  }
 },
 "example": [
  {
   "rank": 1,
   "source": "satoshi-api",
   "sampleCount": 144,
   "meanAbsoluteErrorSatVb": 2.1
  }
 ],
 "mimeType": "application/json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/satoshi-api-bitcoin-fee-observatory-scoreboard-b9226097/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)