# Fathom Macroeconomic Data API — Related Series

> Fathom Macroeconomic Data API — Related Series is a paid API for AI agents from fredfathom.vercel.app, paid per call via x402, $0.04/call, status unknown (last checked 2026-10-12).

Returns FRED series related to a given FRED series ID, including category metadata

## Facts

- Endpoint: POST https://fredfathom.vercel.app/api/related?utm_source=zero.xyz
- Price: $0.04/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fathom-macroeconomic-data-api-related-series-46f680f3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_BtjOhMPhKDJwhXP8jEGwi

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-46f680f3 -d '<json body>'
```

Example prompt: What FRED series are related to UNRATE (the US unemployment rate)? I want to explore other datasets connected to it.

## When to prefer this

Choose this endpoint when you need to discover which FRED categories a specific economic series belongs to, or want to find related macroeconomic datasets programmatically without browsing the FRED website. Ideal for agents building economic research tools, dashboards, or automated data pipelines that need to traverse the FRED taxonomy. Prefer this over the main series-fetch endpoints when the goal is exploration and discovery rather than retrieving actual time series values.

## Known failure modes

- Invalid or non-existent FRED series ID returns an error or empty categories array
- Network timeout on the Vercel-hosted endpoint
- Payment failure if USDC balance is insufficient for the $0.04 per-call fee
- Rate limiting or quota exhaustion on the underlying FRED API

## 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 with the data source attribution, the queried series ID, and an array of category objects describing the categories that FRED associates with the given series — enabling discovery of related economic time series within the same classification hierarchy.

## 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-46f680f3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fredfathom.vercel.app](https://www.zero.xyz/host/fredfathom.vercel.app/llms.txt)