# ENS Reverse Resolution

> ENS Reverse Resolution is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-29).

Resolves an Ethereum address to its primary ENS (Ethereum Name Service) name

## Facts

- Endpoint: POST https://twin.unykorn.org/ens-reverse?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ens-reverse-resolution-7430f529
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_DP9X_TXt8aUwxz6C3OmLg

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 ens-reverse-resolution-7430f529 -d '<json body>'
```

Example prompt: What's the primary ENS name registered to the Ethereum address 0x4bbeEB066eD09B7AEd07bF39EEe0460DFa261520?

## When to prefer this

Use this endpoint when you need to translate a raw Ethereum address into a human-readable ENS name, particularly for display purposes, identity verification, or enriching on-chain data. Prefer this over on-chain direct calls when you need a managed, pay-per-use API with receipts and no RPC node setup required. Best suited for agents that already handle x402 micropayments and need ENS reverse lookup as part of a blockchain data pipeline.

## Known failure modes

- Address has no primary ENS name set — returns ok: true but with null or empty name field
- Invalid Ethereum address format (not matching ^0x[0-9a-fA-F]{40}$) — returns 400 error
- ENS resolver or Ethereum node is unavailable — may return 503 or timeout
- Payment failure via x402 protocol — returns 402 Payment Required
- Address is valid but ENS reverse record points to a name that no longer forward-resolves to the same address — may return mismatched or stale result

## How this service works

Reverse-resolve an address to its primary ENS name — Genesis402 / UnyKorn Operator Network

## Output

Returns a JSON object indicating success (ok: true), the type field 'ens-reverse', and a receipt containing a transaction hash, USD amount charged, and a unique receipt ID, along with a generated_at ISO8601 timestamp. The primary ENS name for the address is included in the response payload.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "params": {
   "type": "object",
   "properties": {
    "address": {
     "type": "string",
     "pattern": "^0x[0-9a-fA-F]{40}$"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "type": "ens-reverse",
  "receipt": {
   "tx_hash": "0x<64hex>",
   "amount_usd": 0.25,
   "receipt_id": "g402-<16hex>"
  },
  "generated_at": "<iso8601>"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ens-reverse-resolution-7430f529/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from twin.unykorn.org](https://www.zero.xyz/host/twin.unykorn.org/llms.txt)