# ChainRead Nonce Lookup

> ChainRead Nonce Lookup is a paid API for AI agents from api.firstmention.uk, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-29).

Retrieves the nonce (transaction count) for a blockchain address on Base or Ethereum, useful for transaction sequencing and wallet analysis.

## Facts

- Endpoint: POST https://api.firstmention.uk/s/chainread/nonce?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/chainread-nonce-lookup-40a18d77
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_N4VL0DrcDDnFqm1d2fVzy

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 chainread-nonce-lookup-40a18d77 -d '<json body>'
```

Example prompt: What is the current nonce for the address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base — and does it show any risk flags?

## When to prefer this

Use this endpoint when you need on-chain nonce data for an address on Base or Ethereum, especially when combined with risk scoring and flagging. Prefer it over raw RPC calls when you want structured risk metadata alongside the nonce, or when building agents that need pay-per-call blockchain reads without managing infrastructure. Best for AI agents that need transaction sequencing data plus compliance-grade risk context in a single call.

## Known failure modes

- Invalid or malformed 0x address returns an error
- Unsupported chain value (not 'base' or 'ethereum') returns a validation error
- Payment failure via x402/USDC results in 402 Payment Required
- Network or RPC node unavailability causes timeout or 503
- Address with no on-chain history may return minimal data or zero nonce

## How this service works

Pay-per-call HTTP APIs, paid with x402 in USDC on Base (eip155:8453): agentkit, api-change-check, basedue, basewatch, chainread, check-sanctions, chgwatch, company-facts, composite, edgar, feednews, pageaudit, solcheck, token-dd, txpreflight, walletcheck, webmd, webread, websearch, x402index. Each operation describes its service.

## Output

Returns a JSON object containing the blockchain address, chain, nonce-derived risk score (0-100), a verdict (e.g. CAUTION, SAFE, RISKY), an array of flags with severity levels (e.g. owner_holds_power: high), and metadata including the payer address and price paid in USD.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "hash": {
   "type": "string",
   "description": "0x transaction hash (for /tx)"
  },
  "chain": {
   "enum": [
    "base",
    "ethereum"
   ],
   "type": "string"
  },
  "number": {
   "type": "string",
   "description": "Block number or 'latest' (for /block)"
  },
  "address": {
   "type": "string",
   "description": "0x address or ERC-20 contract address"
  },
  "addresses": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "description": "Up to 25 addresses (for /batch)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "risk": "medium",
  "_meta": {
   "payer": "0x...",
   "price_usd": 0.01
  },
  "chain": "base",
  "flags": [
   {
    "code": "owner_holds_power",
    "severity": "high"
   }
  ],
  "score": 45,
  "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
  "verdict": "CAUTION"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/chainread-nonce-lookup-40a18d77/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.firstmention.uk](https://www.zero.xyz/host/api.firstmention.uk/llms.txt)