# Base Token Facts API

> Base Token Facts API is a paid API for AI agents from base-facts.yankii.fr, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-11).

Returns on-chain metadata and analysis for a given ERC-20 token contract on the Base blockchain, including name, symbol, decimals, supply, proxy status, and detected admin functions.

## Facts

- Endpoint: POST https://base-facts.yankii.fr/v1/facts?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-token-facts-api-6ca5110c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-2FdqajYpNi5wF6uhzZLl

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-token-facts-api-6ca5110c -d '<json body>'
```

Example prompt: Can you pull the on-chain facts for the token at 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on Base — I want to know its name, symbol, total supply, whether it's a proxy, and what admin functions like mint or pause it has?

## When to prefer this

Use this endpoint when you need authoritative on-chain facts about a specific token contract deployed on the Base network, especially when you need proxy architecture details, admin function detection (mint, burn, pause, blacklist), and owner information in a single call. Prefer this over generic block explorers when you need structured, machine-readable output suitable for automated DeFi risk assessment or smart contract auditing workflows on Base specifically.

## Known failure modes

- Invalid or non-0x-prefixed address returns an error or empty result
- Address is an EOA (not a contract) — isContract may be false and ERC-20 fields may be absent
- Token is not ERC-20 compliant — contractType may be unknown or fields may be null
- RPC timeout or Base network congestion causing slow or failed response
- Non-Base-network contract addresses will not return meaningful results
- Unverified or minimal contracts may return sparse admin function data

## How this service works

Get on-chain facts about a Base token contract

## Output

A JSON object containing: ERC-20 token metadata (name, symbol, decimals, totalSupply), the contract owner address, proxy details (isProxy, standard such as ZeppelinOS, implementation address), whether the address is a contract, the contract type (e.g. ERC20), the block number at which the data was fetched, the data source (base-mainnet-rpc), and a map of detected admin functions (burn, mint, owner, pause, blacklist).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "token": {
   "type": "string",
   "description": "Token contract address (0x-prefixed hex, 20 bytes)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "erc20": {
   "name": "USD Coin",
   "symbol": "USDC",
   "decimals": 6,
   "totalSupply": "4375220680762469"
  },
  "owner": "0x3ABd6f64A422225E61E435baE41db12096106df7",
  "proxy": {
   "isProxy": true,
   "standard": "ZeppelinOS",
   "implementation": "0x2Ce6311ddAE708829bc0784C967b7d77D19FD779"
  },
  "source": "base-mainnet-rpc",
  "isContract": true,
  "blockNumber": "52125591",
  "contractType": "ERC20",
  "adminFunctionsDetected": {
   "burn": true,
   "mint": true,
   "owner": true,
   "pause": true,
   "blacklist": true
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-token-facts-api-6ca5110c/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)