# Fathom Macroeconomic Data API — Compare Series

> Fathom Macroeconomic Data API — Compare Series is a paid API for AI agents from fsthum.vercel.app, paid per call via x402, $0.35/call, status unknown (last checked 2026-10-27).

Compares 2–5 FRED economic time series side-by-side, returning aligned observations for cross-series macroeconomic analysis.

## Facts

- Endpoint: POST https://fsthum.vercel.app/api/compare?utm_source=zero.xyz
- Price: $0.35/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-27
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fathom-macroeconomic-data-api-compare-series-4fe5bef2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_V1CejMKik9-tIdrx3D8fx

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-compare-series-4fe5bef2 -d '<json body>'
```

Example prompt: Pull the last 20 observations for FRED series GDP, UNRATE, and CPIAUCSL and show me how they compare side by side.

## When to prefer this

Choose this endpoint when you need to compare multiple FRED macroeconomic time series simultaneously in a single call — ideal for correlation analysis, dashboard building, or research that requires aligned observations across indicators like GDP, CPI, unemployment, and interest rates. Prefer this over single-series endpoints when cross-series comparison is the core goal.

## Known failure modes

- Invalid or non-existent FRED series ID returns an error or empty data for that series
- Requesting fewer than 2 or more than 5 series IDs may be rejected
- Non-numeric or malformed limit value may cause default behavior or error
- FRED upstream downtime may result in empty or stale comparison data
- Payment failure (x402) prevents the call from being 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

A JSON object containing a 'source' string (FRED attribution) and a 'comparison' object with aligned time series observations for each requested FRED series ID, enabling direct cross-series temporal comparison.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "seriesIds"
 ],
 "properties": {
  "limit": {
   "type": "string",
   "description": "Observations per series (default: 10)"
  },
  "seriesIds": {
   "type": "array",
   "description": "Array of 2-5 FRED series IDs to compare"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "source"
 ],
 "properties": {
  "source": {
   "type": "string"
  },
  "comparison": {
   "type": "object"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fathom-macroeconomic-data-api-compare-series-4fe5bef2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fsthum.vercel.app](https://www.zero.xyz/host/fsthum.vercel.app/llms.txt)