# Base Basename Resolver API

> Base Basename Resolver API is a paid API for AI agents from base-facts.yankii.fr, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-11).

Resolves a Base blockchain Basename (e.g. jesse.base.eth) to its on-chain address, or looks up the primary Basename for a given address, using live Base mainnet RPC data.

## Facts

- Endpoint: POST https://base-facts.yankii.fr/v1/basename?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-basename-resolver-api-a2bf5db6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0cyJnNotvpPP3uePL1ZN1

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 base-basename-resolver-api-a2bf5db6 -d '<json body>'
```

Example prompt: Can you resolve jesse.base.eth to its actual on-chain Ethereum address using the Base blockchain?

## When to prefer this

Use this endpoint when you need real-time, on-chain resolution of Base Basenames (.base.eth) to Ethereum addresses or vice versa, especially when accuracy matters (it performs forward-resolution verification). Prefer this over ENS mainnet resolvers when dealing specifically with Base L2 identities, and over cached/off-chain lookup services when freshness is required.

## Known failure modes

- Name not found: Basename is not registered or does not resolve to any address
- Address has no primary Basename registered, returning null name
- Invalid input: neither a valid .base.eth name nor a valid Ethereum address provided
- RPC timeout or Base node unavailability causing failed resolution
- Forward-resolution mismatch: address provided does not verify back to the claimed Basename

## How this service works

Resolve a Basename to an address or an address to its primary Basename

## Output

Returns a JSON object containing the resolved Basename, the on-chain Ethereum address it maps to, the resolver contract address, the block number at which the data was fetched, and the RPC source used (e.g. base-mainnet-rpc).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "name": {
   "type": "string",
   "description": "Basename to resolve to an address, e.g. jesse.base.eth"
  },
  "address": {
   "type": "string",
   "description": "Address whose primary Basename to look up (verified by forward resolution)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "name": "jesse.base.eth",
  "source": "base-mainnet-rpc",
  "address": "0x2211d1D0020DAEA8039E46Cf1367962070d77DA9",
  "resolver": "0xC6d566A56A1aFf6508b41f6c90ff131615583BCD",
  "blockNumber": "52131900"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-basename-resolver-api-a2bf5db6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from base-facts.yankii.fr](https://www.zero.xyz/host/base-facts.yankii.fr/llms.txt)