# ENS Reverse Resolution (x402)

> ENS Reverse Resolution (x402) is a paid API for AI agents from ens-resolve.frcompanycheck.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-16).

Resolves an Ethereum address to its ENS name (reverse lookup) with forward verification, paid per-call via x402 USDC on Base.

## Facts

- Endpoint: GET https://ens-resolve.frcompanycheck.workers.dev/v1/reverse/%7Baddress%7D?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ens-reverse-resolution-x402-d3452c8f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_9ZMxIg4xyqAFn45AJB_yq

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-x402-d3452c8f
```

Example prompt: What's the ENS name for the Ethereum address 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045? Do a reverse lookup and tell me if it's verified.

## When to prefer this

Use this endpoint when you need to resolve an Ethereum address to a human-readable ENS name with forward verification in a pay-per-call model — ideal for agents that do infrequent or on-demand lookups without a monthly subscription. Prefer this over running your own ENS resolution infrastructure or using a full node provider, especially for lightweight agent workflows that need verified reverse ENS lookups on Ethereum mainnet.

## Known failure modes

- Address has no reverse ENS record set (found: false)
- Forward verification fails — reverse name resolves to a different address (verified: false)
- Invalid or malformed Ethereum address returns an error
- x402 payment failure or insufficient USDC balance blocks the request
- Public RPC rate limits or downtime cause temporary lookup failures

## How this service works

Pay-per-call ENS forward and reverse resolution for AI agents on Ethereum. Resolves name→address and address→name with forward verification. Public Ethereum RPCs + ENS registry only. x402 USDC on Base.

## Output

Returns a JSON object with the ENS name (e.g. 'vitalik.eth'), a 'found' boolean indicating whether a reverse record exists, the verified canonical address, and a 'verified' flag confirming the forward resolution matches the input address.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "name": "vitalik.eth",
  "found": true,
  "address": "0xd8da6bf26964af9d7eed9e03e53415d37aa96045",
  "verified": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ens-reverse-resolution-x402-d3452c8f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from ens-resolve.frcompanycheck.workers.dev](https://www.zero.xyz/host/ens-resolve.frcompanycheck.workers.dev/llms.txt)