# Northline ChainKit Address Profile

> Northline ChainKit Address Profile is a paid API for AI agents from northline-chainkit.northline-c86.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-31).

Returns onchain profile information for an Ethereum address on Base or Arc, including whether it is a contract, token type, proxy status, and ERC metadata.

## Facts

- Endpoint: GET https://northline-chainkit.northline-c86.workers.dev/v1/address/profile?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/northline-chainkit-address-profile-c4713d08
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_q3y-kELUSzC_MDJ7iBeI9

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 northline-chainkit-address-profile-c4713d08
```

Example prompt: Can you look up the onchain profile for the address 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 on Base — I want to know if it's a contract, whether it's an upgradeable proxy, and what token it represents?

## When to prefer this

Use this endpoint when you need a quick, pay-per-call onchain lookup of an Ethereum-compatible address specifically on Base or Arc — especially when you want contract classification, proxy detection (EIP-1967), and token metadata in a single call without running your own node or indexer. Prefer this over generic block explorers when you need structured JSON output suitable for agent pipelines.

## Known failure modes

- Invalid address format (must match ^0x[0-9a-fA-F]{40}$) returns a validation error
- Address not found or not deployed on the specified chain returns empty or null profile
- Unsupported chain value (anything other than 'base' or 'arc') returns a parameter error
- Payment failure via x402 protocol results in 402 response before query is executed
- Network or RPC timeout for the underlying chain returns a 503 or timeout error

## How this service works

x402 pay-per-call onchain API (Base + Arc).

## Output

A JSON object containing the address kind (e.g. 'contract' or 'eoa'), the chain it was queried on, an array of flags such as 'upgradeable_proxy', proxy details including the EIP-1967 implementation address, and token metadata such as symbol and decimals if the address is a token contract.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address"
     ],
     "properties": {
      "chain": {
       "enum": [
        "base",
        "arc"
       ],
       "type": "string",
       "default": "base"
      },
      "address": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "kind": "contract",
  "chain": "base",
  "flags": [
   "upgradeable_proxy"
  ],
  "proxy": {
   "eip1967Implementation": "0x2ce6311ddae708829bc0784c967b7d77d19fd779"
  },
  "token": {
   "symbol": "USDC",
   "decimals": 6
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/northline-chainkit-address-profile-c4713d08/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from northline-chainkit.northline-c86.workers.dev](https://www.zero.xyz/host/northline-chainkit.northline-c86.workers.dev/llms.txt)