# Fathom Macroeconomic Data API — Related Series Lookup

> Fathom Macroeconomic Data API — Related Series Lookup is a paid API for AI agents from fathoms.vercel.app, paid per call via x402, $0.04/call, status unknown (last checked 2026-09-14).

Returns related FRED economic time series and categories for a given FRED series ID

## Facts

- Endpoint: POST https://fathoms.vercel.app/api/related
- Price: $0.04/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fathom-macroeconomic-data-api-related-series-lookup-301f3098
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_nwzxYu1LFVf1_s7O9zgOd

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 fathom-macroeconomic-data-api-related-series-lookup-301f3098 -d '<json body>'
```

Example prompt: Can you find FRED economic series related to UNRATE (the US unemployment rate) and show me what categories and related indicators come up?

## When to prefer this

Use this endpoint when you need to discover what economic indicators are related to a known FRED series ID — ideal for exploring the FRED taxonomy, building economic dashboards with related data, or finding adjacent indicators for research. Prefer this over a general FRED series search when you already have a specific series ID and want to understand its categorical context and related series.

## Known failure modes

- Invalid or non-existent FRED series ID returns an error or empty categories array
- Missing required seriesId field returns a validation error
- FRED upstream outage may cause failed or stale responses
- Rate limits or payment failures (x402) will block access
- Very obscure or deprecated series IDs may return no related categories

## How this service works

Free macroeconomic data API powered by FRED. 816,000+ economic time series. GDP, inflation, unemployment, interest rates, and more.

## Output

Returns a JSON object containing the data source attribution, the queried series ID, and an array of related category objects — each describing a FRED category that the series belongs to or is associated with, enabling discovery of adjacent economic indicators.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "seriesId"
 ],
 "properties": {
  "seriesId": {
   "type": "string",
   "description": "FRED series ID"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "source"
 ],
 "properties": {
  "source": {
   "type": "string"
  },
  "series_id": {
   "type": "string"
  },
  "categories": {
   "type": "array",
   "items": {
    "type": "object"
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fathom-macroeconomic-data-api-related-series-lookup-301f3098/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fathoms.vercel.app](https://www.zero.xyz/host/fathoms.vercel.app/llms.txt)