Developer Utilities Tier 3 Ready POST /v1/cron-explainer

Cron Expression Explainer & Next-Runs Calculator API — 5/6/7-Field & Timezones

Validate cron expressions, translate to plain English, and compute next N runs with DST. Validate standard 5-field, 6-field (seconds), AWS/Quartz, and @macros cron expressions, translate them to plain English, and compute next N runs with DST.

Try It Live in Your Browser · No API Key Required

1. Interactive Sandbox & Sample JSON Output

200 OK · Ready

Editable Request JSON (`POST /v1/cron-explainer`)

Live 200 OK Response Envelope

{
  "ok": true,
  "data": {
    "valid": true,
    "normalized_expression": "0 9 * * 1-5",
    "format": "5-field",
    "timezone": "Europe/Budapest",
    "explanation": "At 09:00, Monday through Friday (Europe/Budapest)",
    "fields": {
      "seconds": "0",
      "minutes": "0",
      "hours": "9",
      "day_of_month": "*",
      "month": "*",
      "day_of_week": "1-5"
    },
    "next_runs": [
      {
        "iso_utc": "2026-11-16T08:00:00.000Z",
        "local_time": "2026-11-16T09:00:00+01:00",
        "epoch_ms": 1794816000000,
        "utc_offset": "+01:00"
      },
      {
        "iso_utc": "2026-11-17T08:00:00.000Z",
        "local_time": "2026-11-17T09:00:00+01:00",
        "epoch_ms": 1794902400000,
        "utc_offset": "+01:00"
      },
      {
        "iso_utc": "2026-11-18T08:00:00.000Z",
        "local_time": "2026-11-18T09:00:00+01:00",
        "epoch_ms": 1794988800000,
        "utc_offset": "+01:00"
      },
      {
        "iso_utc": "2026-11-19T08:00:00.000Z",
        "local_time": "2026-11-19T09:00:00+01:00",
        "epoch_ms": 1795075200000,
        "utc_offset": "+01:00"
      },
      {
        "iso_utc": "2026-11-20T08:00:00.000Z",
        "local_time": "2026-11-20T09:00:00+01:00",
        "epoch_ms": 1795161600000,
        "utc_offset": "+01:00"
      }
    ],
    "warnings": [],
    "errors": []
  },
  "meta": {
    "request_id": "req_cron_01",
    "ms": 2
  }
}

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2. Quickstart Code Examples

Full TypeScript & Python SDK →

curl -X POST "https://api.tinplate.dev/v1/cron-explainer" \
  -H "Content-Type: application/json" \
  -H "X-RapidAPI-Key: YOUR_RAPIDAPI_KEY" \
  -d '{"expression":"0 9 * * 1-5","timezone":"Europe/Budapest","next_runs":3,"reference_time":"2026-11-14T08:00:00Z"}'

import { TinplateClient } from "@tinplate/sdk"; // npm install @tinplate/sdk

const tinplate = new TinplateClient({
  rapidApiKey: process.env.RAPIDAPI_KEY!,
});

const { data, meta } = await tinplate.call("/v1/cron-explainer", {
  "expression": "0 9 * * 1-5",
  "timezone": "Europe/Budapest",
  "next_runs": 3,
  "reference_time": "2026-11-14T08:00:00Z"
});
console.log(`[${meta.ms} ms]`, data);

import requests

response = requests.post(
    "https://api.tinplate.dev/v1/cron-explainer",
    headers={
        "Content-Type": "application/json",
        "X-RapidAPI-Key": "YOUR_RAPIDAPI_KEY",
    },
    json={
  "expression": "0 9 * * 1-5",
  "timezone": "Europe/Budapest",
  "next_runs": 3,
  "reference_time": "2026-11-14T08:00:00Z"
}
)
print(response.json())

const response = await fetch("https://api.tinplate.dev/v1/cron-explainer", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "X-RapidAPI-Key": "YOUR_RAPIDAPI_KEY",
  },
  body: JSON.stringify({
  "expression": "0 9 * * 1-5",
  "timezone": "Europe/Budapest",
  "next_runs": 3,
  "reference_time": "2026-11-14T08:00:00Z"
}),
});
const result = await response.json();
console.log(result);

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "tinplate_cron_explainer",
    "arguments": {
      "expression": "0 9 * * 1-5",
      "timezone": "Europe/Budapest",
      "next_runs": 3,
      "reference_time": "2026-11-14T08:00:00Z"
    }
  }
}

OpenAPI 3.0.3 Schema Contract

Request Parameters & Response Schema Reference

Request Body Parameters (`POST /v1/cron-explainer`)

Parameter	Type & Constraints	Description
`expression`required	`string` minLen: 1, maxLen: 256	5-field UNIX cron, 6-field cron (with leading seconds), or macro (@hourly, @daily, @weekly, @monthly, @yearly, @reboot). Supports L, W, and #.
`timezone`optional	`string` minLen: 1, maxLen: 64, default: "UTC"	IANA timezone name (e.g. 'UTC', 'Europe/Budapest', 'America/New_York').
`count`optional	`integer` min: 1, max: 50, default: 5	Number of upcoming execution times to compute (1 to 50).
`from_time`optional	`string`	Optional ISO-8601 starting timestamp (defaults to current UTC time).

Response `data` Object Fields (`200 OK`)

Field	Type	Description
`valid`	`boolean`	Field 'valid'
`normalized_expression`	`string \| null`	Field 'normalized_expression'
`format`	`"5-field" \| "6-field" \| "macro" \| "reboot" \| "invalid"`	Field 'format'
`timezone`	`string`	Field 'timezone'
`explanation`	`string \| null`	Field 'explanation'
`fields`	`object \| null`	Field 'fields'
`next_runs`	`object[]`	Field 'next_runs'
`warnings`	`string[]`	Field 'warnings'
`errors`	`string[]`	Field 'errors'

3. What Cron & Schedule Explainer & Validator API Detects & Validates

Supports POSIX 5-field, 6-field (with seconds), Quartz/AWS extensions (L, W, #), and @hourly/@daily/@weekly/@monthly macros
Human-readable English summary of any schedule
Computes next N occurrences in any IANA timezone (e.g. Europe/Budapest, America/New_York) with DST transition warnings
Flags footguns like simultaneous day-of-month and day-of-week OR semantics

Honest Engineering Boundaries

4. Known Limitations & Test Verification

Release Version: v1.0.7 · Last Verified / Benchmarked: 14 November 2026 · Latency Note: Sub-millisecond figures measure in-Worker V8 compute time (typical client HTTPS network RTT to the nearest Cloudflare PoP is 15–65 ms) · See Full Portfolio Benchmarks & Corpora →

Computes up to 50 future occurrences per request within a 5-year lookahead window.
Tested v1.0.4 (14 November 2026).

5. Marketplace Plans & Payload Quotas

Plan	Monthly Price	Included Requests	Rate Limit	Max Request Payload	Best For
BASIC	$0.00 / month	500 / month (hard limit)	10 req / min	64 KB	Evaluation, local development & CI smoke tests
PRO	$9.99 / month	15,000 / month	60 req / min	128 KB	Solo developers & production apps
ULTRA	$29.99 / month	100,000 / month	300 req / min	256 KB	Growing SaaS & multi-agent pipelines
MEGA	$79.99 / month	500,000 / month	1,000 req / min	256 KB	High-volume enterprise workloads

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6. Frequently Asked Questions

Does it warn about the classic DOM + DOW cron trap?

Yes! In standard POSIX cron, specifying both day-of-month and day-of-week uses OR logic rather than AND. The API explicitly warns when both are restricted.

Does it support IANA timezones and Daylight Saving Time?

Yes, pass any IANA timezone name (e.g. Europe/Budapest) and it calculates exact local offsets and flags spring-forward/fall-back DST jumps.

Are @daily, @weekly, and 6-field seconds supported?

Yes, both standard macros and 6-field second-precision cron strings are supported.

Zero Payload Logging

7. Data Handling, Privacy & Marketplace Proxy Disclosure

Pure deterministic calculation in V8 memory.

Worker Zero-Logging Guarantee: Cloudflare Workers Observability and invocation logging are disabled in configuration (observability.enabled = false, head_sampling_rate = 0, invocation_logs = false). Payloads are processed strictly in volatile V8 memory and never logged or stored by Tinplate.

Marketplace Proxies vs. Direct Bearer Key: Requests sent via RapidAPI or Zyla API Hub pass through those marketplaces' proxy infrastructure (subject to their respective privacy policies). Security-sensitive workloads requiring end-to-end zero-intermediary processing can connect directly to https://api.tinplate.dev using a Direct Bearer Key (Authorization: Bearer <API_KEY>). Read our full Privacy Notice and OpenAPI 3.0.3 JSON Schema.