# x402engine ENS Reverse Lookup

> x402engine ENS Reverse Lookup is a paid API for AI agents from x402engine.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Resolves an Ethereum address to its ENS (Ethereum Name Service) human-readable name via a pay-per-call micropayment API.

## Facts

- Endpoint: GET https://x402engine.app/api/ens/reverse
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402engine-ens-reverse-lookup-f48d4fb1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_G2TAFPb26PmXgfV45-Hfl

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 x402engine-ens-reverse-lookup-f48d4fb1
```

Example prompt: What's the ENS name registered to the Ethereum address 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045?

## When to prefer this

Use this endpoint when you need to resolve a raw Ethereum 0x address to its ENS name, especially in agent workflows that require human-readable Web3 identities or on-chain identity enrichment. Prefer this over building your own ENS resolution when you need a pay-per-call, no-subscription model accessible via HTTP.

## Known failure modes

- Address has no ENS reverse record set — returns null or empty name
- Invalid or malformed Ethereum address — returns 400 or validation error
- Payment failure via x402 micropayment protocol — returns 402
- ENS resolver or upstream node unavailable — returns 500 or timeout

## How this service works

Reverse-resolve an Ethereum address to its ENS name

## Output

Returns the ENS human-readable name (e.g. 'vitalik.eth') associated with the provided Ethereum address, or an indication that no reverse record exists for that address.

## 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",
     "required": [
      "address"
     ],
     "properties": {
      "address": {
       "type": "string",
       "example": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
       "description": "Ethereum address (0x...)"
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402engine-ens-reverse-lookup-f48d4fb1/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402engine.app](https://www.zero.xyz/host/x402engine.app/llms.txt)