# EVM Batch Duplicate Nonce Check

> EVM Batch Duplicate Nonce Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Checks an array of EVM transaction nonces for duplicates and returns which nonces appear more than once.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/evm-batch-duplicate-nonce-check
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/evm-batch-duplicate-nonce-check-8bb4a2cf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_R4ujq8v81mxQaqWOABMRh

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 evm-batch-duplicate-nonce-check-8bb4a2cf -d '<json body>'
```

Example prompt: Before I submit my batch of EVM transactions, check these nonces for duplicates: [5, 11, 3, 11, 7, 5] — tell me if any are repeated and which ones.

## When to prefer this

Use this endpoint when you need a fast, in-memory, privacy-preserving check for duplicate nonces across a batch of EVM transactions before submission. Prefer it over manual deduplication logic in your agent when you need an auditable preflight step with input hashing and a clear advisory status. Ideal for batch transaction pipelines, multicall builders, or any workflow where nonce uniqueness is a safety requirement.

## Known failure modes

- Array exceeds 256-item limit — request rejected
- Non-integer values in nonce array cause validation error
- Empty array input may return trivially unique result
- Malformed JSON body returns 400 error

## How this service works

EVM Batch Duplicate Nonce Check: EVM Batch Duplicate Nonce Check finds duplicate nonces inside a caller-supplied transaction batch from bounded caller-supplied values without an external provider. Call EVM Batch Duplicate Nonce Check before signing, submitting, replacing, or accepting an EVM/Base transaction assembled from caller-owned data. Returns normalized transaction evidence, calculated budget or shape findings, and a fail-closed preflight status for EVM Batch Duplicate Nonce Check as ver…

## Output

Returns a JSON object indicating whether all nonces are unique (boolean 'unique' field), and an array 'duplicate_nonces' listing any integer nonces that appear more than once in the input. Also includes operation metadata such as whether input was retained (always false) and an input SHA-256 hash for auditability.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "nonces": {
   "type": "array",
   "items": {
    "type": "integer"
   },
   "maxItems": 256,
   "description": "Nonces supplied to EVM Batch Duplicate Nonce Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "unique": false,
   "duplicate_nonces": [
    11
   ]
  },
  "schema": "delx/util-evm-batch-duplicate-nonce-check/v1",
  "status": "advisory",
  "evidence": {
   "retained": false,
   "input_sha256": "93258878a4b3e2c7cf1c455a9ed9b67ff3017ff1d070d0d1a079a29ac92b1af4",
   "external_calls": 0
  },
  "operation": "evm_preflight:evm_batch_duplicate_nonce_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/evm-batch-duplicate-nonce-check-8bb4a2cf/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)