# Last Modified Compare

> Last Modified Compare is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-15).

Compares two Last-Modified HTTP timestamps (as Unix epochs) and computes their delta against caller-supplied bounds, returning a pass/advisory status with normalized evidence.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/last-modified-compare?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/last-modified-compare-b5e75fd2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_lDRlV3w4xD7_AEUlbRKNV

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 last-modified-compare-b5e75fd2 -d '<json body>'
```

Example prompt: Compare two Last-Modified timestamps for me — the before epoch is 1700000000 and the after epoch is 1700086400 — and tell me if the ordering and delta look valid, with a pass or advisory verdict.

## When to prefer this

Use this endpoint when an agent needs a deterministic, stateless verdict on whether two Last-Modified HTTP timestamps are correctly ordered and within acceptable delta bounds — particularly before caching, accepting, redirecting, or retrying a web response. Prefer it over manual timestamp arithmetic when you need a normalized, auditable JSON result with an explicit pass/advisory classification rather than raw computation.

## Known failure modes

- Missing or invalid after_epoch or before_epoch integers — request rejected or malformed response
- after_epoch earlier than before_epoch — may return advisory status rather than pass
- Epochs outside plausible Unix timestamp range — validation may flag as anomalous
- Payment failure via x402 protocol — endpoint returns 402 before processing

## How this service works

Last Modified Compare: Last Modified Compare orders two Last-Modified instants and reports their delta from bounded caller-supplied values without an external provider. Call Last Modified Compare 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 Last Modified Compare as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-party, stateless, memo…

## Output

Returns a versioned deterministic JSON object containing: normalized Last-Modified evidence extracted from the inputs, the computed delta between the two epochs, and an explicit pass or advisory status indicating whether the timestamps satisfy the bounded comparison criteria.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "after_epoch": {
   "type": "integer",
   "description": "After Epoch supplied to Last Modified Compare; used only for this bounded calculation and processed in memory without retention."
  },
  "before_epoch": {
   "type": "integer",
   "description": "Before Epoch supplied to Last Modified Compare; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "direction": "newer",
   "delta_seconds": 120
  },
  "schema": "delx/util-last-modified-compare/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "3af22a08d2240acef2720f15dceafc3801c8b2b7dffd60a82da13e82ad1839fb",
   "external_calls": 0
  },
  "operation": "web_reliability:last_modified_compare"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/last-modified-compare-b5e75fd2/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)