# Fathom Macroeconomic Data API — Related Series Lookup

> Fathom Macroeconomic Data API — Related Series Lookup is a paid API for AI agents from fredthom.vercel.app, paid per call via x402, $0.35/call, status unknown (last checked 2026-09-14).

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

## Facts

- Endpoint: POST https://fredthom.vercel.app/api/related
- Price: $0.35/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-1a420936
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_xQ_4pJCDF3TeWqkTXM4Jl

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-1a420936 -d '<json body>'
```

Example prompt: What FRED series are related to GDP (series ID 'GDP')? I want to discover other connected economic indicators and which categories they fall under.

## When to prefer this

Use this endpoint when you have a known FRED series ID and want to discover related or adjacent economic data series and their categories, enabling exploration of the FRED data graph. Prefer this over a general search when you already know the anchor series and want to branch out to related indicators.

## Known failure modes

- Invalid or unknown FRED series ID returns empty or error response
- Network timeout if FRED upstream is slow
- Missing required seriesId field returns a validation error
- Series ID with no related series returns empty categories array

## 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 source attribution (FRED), the queried series ID, and an array of related series objects including their categories — useful for navigating the FRED data graph and discovering related 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-1a420936/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fredthom.vercel.app](https://www.zero.xyz/host/fredthom.vercel.app/llms.txt)