# Fathom Macroeconomic Data API — Category Series Lookup

> Fathom Macroeconomic Data API — Category Series Lookup is a paid API for AI agents from fredthom.vercel.app, paid per call via x402, $0.4/call, status unknown (last checked 2026-09-14).

Returns a list of FRED economic time series belonging to a specified category, such as GDP, inflation, or unemployment series.

## Facts

- Endpoint: POST https://fredthom.vercel.app/api/category-series
- Price: $0.4/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-category-series-lookup-f997b860
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VG9qFq-14i3BWEFNFtwgT

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-category-series-lookup-f997b860 -d '<json body>'
```

Example prompt: Can you show me up to 50 economic time series available under FRED category 32992 — I'm trying to find all the interest rate indicators grouped in that category.

## When to prefer this

Use this endpoint when you need to discover or enumerate all economic time series within a known FRED category, such as exploring what indicators are available under a topic like inflation, GDP, or employment. It is ideal for building data catalogs, letting users browse available series before selecting one to fetch data for, or when you know the FRED category ID but need to find the specific series IDs it contains.

## Known failure modes

- Missing or invalid categoryId returns an error or empty series array
- Non-existent FRED category ID returns empty results with no series
- Upstream FRED API unavailability causes request failure
- Invalid limit parameter type may cause unexpected truncation or error
- Payment failure (x402) blocks access before the query is processed

## How this service works

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

## Output

An array of FRED economic time series objects associated with the given category ID, along with the source attribution string and the category ID used in the query. Each series object typically includes metadata such as series ID, title, frequency, and units.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "categoryId"
 ],
 "properties": {
  "limit": {
   "type": "string",
   "description": "Max results (default: 20)"
  },
  "categoryId": {
   "type": "string",
   "description": "FRED category ID"
  }
 }
}
```

## Response schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fathom-macroeconomic-data-api-category-series-lookup-f997b860/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)