# Fathom — Category Series Lookup (FRED-powered Macroeconomic Data API)

> Fathom — Category Series Lookup (FRED-powered Macroeconomic Data API) is a paid API for AI agents from fathoms.vercel.app, paid per call via x402, $0.06/call, status unknown (last checked 2026-09-15).

Returns the list of economic data series belonging to a given FRED category, such as GDP, inflation, or unemployment series grouped under a category ID.

## Facts

- Endpoint: POST https://fathoms.vercel.app/api/category-series
- Price: $0.06/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fathom-category-series-lookup-fred-powered-macroeconomic-data-api-1c5d0581
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_3eWe29tQX3mmAh2geMXwb

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-category-series-lookup-fred-powered-macroeconomic-data-api-1c5d0581 -d '<json body>'
```

Example prompt: Pull up all the economic time series listed under FRED category 32455 — show me up to 50 series so I can see what GDP-related data is available.

## When to prefer this

Use this endpoint when you need to discover or enumerate what economic time series exist under a specific FRED category — i.e., when you know the category but want to list the series within it. Prefer this over a general series search when you already have a FRED category ID and want to browse its contents systematically. It is particularly useful for building data pipelines or dashboards that need to enumerate available indicators by category.

## Known failure modes

- Invalid or non-existent categoryId returns empty series array or error
- Missing categoryId field causes a 400-level validation error
- Limit parameter set too high may slow response or hit upstream FRED rate limits
- FRED upstream API downtime results in service unavailability
- Non-numeric or malformed categoryId may cause unexpected behavior

## 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 an array of economic time series objects (each with series metadata like ID, title, frequency, units, and dates), the source attribution string ('FRED'), and the requested category ID. The series array contains structured metadata about each data series available under the specified FRED category.

## 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-category-series-lookup-fred-powered-macroeconomic-data-api-1c5d0581/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)