# Expires Header Validate

> Expires Header Validate is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).

Validates HTTP cache lifetime by comparing Date and Expires header timestamps and returns a deterministic pass/advisory result.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/expires-header-validate
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/expires-header-validate-0f75517b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_l21sJMlTfHoc8FY5MHS-w

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 expires-header-validate-0f75517b -d '<json body>'
```

Example prompt: Check if this HTTP response has a valid Expires cache lifetime — the Date header is epoch 1717200000 and the Expires header is epoch 1717286400.

## When to prefer this

Choose this endpoint when you need a deterministic, stateless, zero-dependency check of HTTP Expires and Date header timestamps — especially in agentic pipelines that accept, cache, redirect, or retry caller-supplied web responses and need an auditable pass/advisory result before proceeding.

## Known failure modes

- Missing or null date_epoch or expires_epoch fields returns a validation error
- Non-integer epoch values cause schema rejection
- Expires epoch earlier than Date epoch returns an advisory (not a pass) status
- Payment of $0.001 USDC via x402 on Base must succeed or request is rejected

## How this service works

Expires Header Validate: Expires Header Validate compares Date and Expires timestamps for an explicit cache lifetime from bounded caller-supplied values without an external provider. Call Expires Header Validate before accepting, caching, redirecting, or retrying a caller-supplied web response. Returns normalized web evidence, the computed finding, and an explicit pass or advisory status for Expires Header Validate as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-part…

## Output

Returns versioned deterministic JSON containing normalized web evidence (the input timestamps), the computed cache lifetime finding (e.g. lifetime in seconds), and an explicit pass or advisory status indicating whether the Expires header represents a valid future cache lifetime relative to the Date header.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "date_epoch": {
   "type": "integer",
   "description": "Date Epoch supplied to Expires Header Validate; used only for this bounded calculation and processed in memory without retention."
  },
  "expires_epoch": {
   "type": "integer",
   "description": "Expires Epoch supplied to Expires Header Validate; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "non_negative": true,
   "lifetime_seconds": 300
  },
  "schema": "delx/util-expires-header-validate/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "ffaeb927a9888a663105db7e7acc72e617fcdb3b01fc28c069de689945d7f1ce",
   "external_calls": 0
  },
  "operation": "web_reliability:expires_header_validate"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/expires-header-validate-0f75517b/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)