# Polyform Reverse Geocoding API

> Polyform Reverse Geocoding API is a paid API for AI agents from api.polyform.org, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Converts a geographic coordinate (lat/lng) to US administrative location data including state, county, and census tract

## Facts

- Endpoint: GET https://api.polyform.org/v1/geo/reverse
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/polyform-reverse-geocoding-api-8cd0112a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KOwGs0Y6rSKwsVEOwkZP7

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 polyform-reverse-geocoding-api-8cd0112a
```

Example prompt: What US state, county, and census tract is the coordinate 36.1627° N, 86.7816° W located in?

## When to prefer this

Choose this endpoint when you need lightweight, pay-per-call US reverse geocoding without account setup or API key management. It returns structured administrative identifiers (state, county, census tract) rather than full street addresses, making it ideal for compliance tagging, demographic enrichment, or census analysis workflows. Prefer this over full geocoding services when you only need administrative region classification and want zero-friction micropayment access via USDC on Base.

## Known failure modes

- Coordinate outside the US returns no result or an error — endpoint only covers US geography
- Missing or malformed lat/lng query parameters result in a 400 bad request
- Payment failure (insufficient USDC balance or x402 protocol error) blocks the call
- Coordinates on exact administrative boundary edges may resolve ambiguously

## How this service works

Pay-per-call data endpoints for AI agents. USDC on Base via x402. No account, no API key — one micropayment per call.

## Output

A JSON object containing the US state name, county name, and census tract code (FIPS-style tract identifier) for the provided coordinate, e.g. {"state": "Tennessee", "county": "Davidson County", "tract": "016300"}.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "state": "Tennessee",
  "tract": "016300",
  "county": "Davidson County"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/polyform-reverse-geocoding-api-8cd0112a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.polyform.org](https://www.zero.xyz/host/api.polyform.org/llms.txt)