Cron Expression API

API Documentation

Base URL

https://cron-expr.vercel.app

Authentication

X-API-Key: your_key (header) or ?key=your_key (query)Get your free key below

GET/api/cron?expr=0 9 * * 1-5

Validate a cron expression, get a human-readable description, and calculate the next execution times.

Parameters

ParameterTypeRequiredDescription

exprstringyes5-field cron expression (min hour dom month dow)

countnumbernoNumber of next runs (1-20). Default: 5

tzstringnoTimezone (e.g. America/New_York). Default: UTC

Response

{
  "expression": "0 9 * * 1-5",
  "valid": true,
  "description": "At 09:00 on every day from Monday through Friday",
  "next_runs": [
    "2026-06-17T09:00:00Z",
    "2026-06-18T09:00:00Z",
    "2026-06-19T09:00:00Z",
    "2026-06-20T09:00:00Z",
    "2026-06-21T09:00:00Z"
  ],
  "timezone": "UTC"
}

Error Responses

// 400 — Bad Request
{ "error": "Missing 'expr' parameter..." }

// 401 — Unauthorized
{ "error": "Invalid API key" }

// 429 — Rate Limited
{ "error": "Daily limit reached. Upgrade your plan." }

Get API Key

Get a free API key for 6 requests/day. No credit card required.

Usage

Add header: X-API-Key: your_key
Or query param: ?key=your_key

Limits

Playground (no key): 3 req/day
Free tier (with key): 6 req/day
Paid plans: see pricing below