# Rate Limit Window Check

> Rate Limit Window Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-19).

Checks whether a caller has sufficient remaining quota to fulfill a requested number of API calls given the current time and the rate limit reset epoch, returning a deterministic pass/advisory verdict.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/rate-limit-window-check?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/rate-limit-window-check-8f742051
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bZblAaA4ZwCvEZZgaxg62

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 rate-limit-window-check-8f742051 -d '<json body>'
```

Example prompt: Before I send those 50 requests, check if my rate limit window has enough headroom — I have 30 calls remaining, I want to send 50, the rate limit resets at epoch 1720000000, and the current time is epoch 1719996400.

## When to prefer this

Use this endpoint when an agent needs a deterministic, in-memory quota gate before accepting, caching, redirecting, or retrying outbound calls — especially in agentic pipelines where rate limit logic must be auditable and stateless. Prefer this over ad-hoc client-side quota math when you need a versioned, normalized JSON verdict with explicit pass/advisory output that downstream decision logic can reliably branch on.

## Known failure modes

- Missing or invalid input fields (now_epoch, remaining, requested, reset_epoch) result in a validation error
- Non-integer values for epoch or count fields cause rejection
- Payment failure via x402 prevents the check from executing
- reset_epoch in the past may yield edge-case advisory results

## How this service works

Rate Limit Window Check: Rate Limit Window Check checks remaining quota against reset timing and requested calls from bounded caller-supplied values without an external provider. Call Rate Limit Window Check 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 Rate Limit Window Check as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-party, s…

## Output

Returns versioned deterministic JSON containing: normalized web evidence used in the check, the computed finding (e.g. whether remaining quota covers requested calls relative to reset timing), and an explicit pass or advisory status indicating whether the caller should proceed or hold off.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "now_epoch": {
   "type": "integer",
   "description": "Now Epoch supplied to Rate Limit Window Check; used only for this bounded calculation and processed in memory without retention."
  },
  "remaining": {
   "type": "integer",
   "description": "Remaining supplied to Rate Limit Window Check; used only for this bounded calculation and processed in memory without retention."
  },
  "requested": {
   "type": "integer",
   "description": "Requested supplied to Rate Limit Window Check; used only for this bounded calculation and processed in memory without retention."
  },
  "reset_epoch": {
   "type": "integer",
   "description": "Reset Epoch supplied to Rate Limit Window Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "deficit": 0,
   "within_quota": true,
   "reset_in_seconds": 60
  },
  "schema": "delx/util-rate-limit-window-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "e12bef43e7d52fe13e28d9a9200483561a533bc0eed1e48f817303d9e23b66ee",
   "external_calls": 0
  },
  "operation": "web_reliability:rate_limit_window_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/rate-limit-window-check-8f742051/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)