# EVM Nonce Gap Check

> EVM Nonce Gap 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 whether the gap between a pending and proposed EVM nonce is within a specified maximum budget and whether a replacement is possible.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/evm-nonce-gap-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-nonce-gap-check-317188ed
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ibLFXlgI1c4w9OVGIQeiz

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-nonce-gap-check-317188ed -d '<json body>'
```

Example prompt: Check the EVM nonce gap for me — my pending nonce is 5, I'm proposing nonce 7, and my maximum allowed gap is 1. Is it within budget and is a replacement possible?

## When to prefer this

Use this endpoint when an AI agent or automated system needs to preflight-check EVM transaction nonces before submission to avoid gaps that could cause stuck or dropped transactions. Prefer this over manual calculation when operating in high-frequency or multi-agent transaction environments where nonce management is critical.

## Known failure modes

- Missing required fields (pending_nonce, proposed_nonce, or maximum_gap) may cause validation errors
- Non-integer values for nonce fields will be rejected
- Negative nonce values may produce unexpected results
- Network errors may return 5xx responses

## How this service works

EVM Nonce Gap Check: EVM Nonce Gap Check calculates the gap between pending and proposed transaction nonces from bounded caller-supplied values without an external provider. Call EVM Nonce Gap 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 Nonce Gap Check as versioned deterministic JSON. Price: $0.001 USDC v…

## Output

Returns the computed nonce gap between pending and proposed nonces, a boolean indicating whether the gap is within the specified maximum budget, and a boolean for whether a nonce replacement is possible. Also includes evidence metadata confirming no data is retained and no external calls were made.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "maximum_gap": {
   "type": "integer",
   "description": "Maximum Gap supplied to EVM Nonce Gap Check; used only for this bounded calculation and processed in memory without retention."
  },
  "pending_nonce": {
   "type": "integer",
   "description": "Pending Nonce supplied to EVM Nonce Gap Check; used only for this bounded calculation and processed in memory without retention."
  },
  "proposed_nonce": {
   "type": "integer",
   "description": "Proposed Nonce supplied to EVM Nonce Gap Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "gap": 2,
   "within_budget": false,
   "possible_replacement": false
  },
  "schema": "delx/util-evm-nonce-gap-check/v1",
  "status": "advisory",
  "evidence": {
   "retained": false,
   "input_sha256": "b9889d09b1009c8b22542a020475a3b907ede762b24f2fafec69d286c024edfd",
   "external_calls": 0
  },
  "operation": "evm_preflight:evm_nonce_gap_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/evm-nonce-gap-check-317188ed/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)