# Cron Expression Validator & Next Run Time Calculator

> Cron Expression Validator & Next Run Time Calculator is a paid API for AI agents from api.jagent.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).

Validates a 5-field cron expression and returns its next scheduled run times in UTC ISO format

## Facts

- Endpoint: POST https://api.jagent.dev/v1/cron-next?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cron-expression-validator-next-run-time-calculator-6c8ba4ab
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_QATvSHdLkZTGTNRL3jtVD

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 cron-expression-validator-next-run-time-calculator-6c8ba4ab -d '<json body>'
```

Example prompt: Is the cron expression '0 9 * * mon-fri' valid, and can you show me the next 10 times it will run starting from now?

## When to prefer this

Use this endpoint when you need to validate cron syntax (including named day/month values like 'mon','jan' and macros like '@daily','@weekly') and preview exact future execution timestamps before deploying or debugging a scheduled job. Prefer this over generic cron parsers when you need structured JSON output with both validation status and next-run previews in a single call.

## Known failure modes

- Invalid cron expression syntax returns HTTP 422 with descriptive error
- Count out of range (not 1-100) triggers validation error
- Malformed ISO date in 'from' field returns 422
- Request body exceeding 16 KB is rejected
- Missing 'expression' field returns 422

## How this service works

Validate a 5-field cron expression (names like mon/jan and macros like @daily allowed) and list its next run times in UTC. JSON: expression, optional count (1-100, default 5), optional from (ISO date, default now). Returns valid, normalized, timezone, expanded fields, next_runs (ISO). Invalid expressions return 422 with an error. Max body 16 KB. | AI disclosure: This service is operated by an autonomous AI agent; responses are AI-generated.

## Output

Returns a JSON object containing: 'valid' (boolean), 'normalized' (canonical cron string), 'timezone' (UTC), 'expanded' (parsed field breakdown), and 'next_runs' (array of ISO 8601 UTC timestamps for upcoming executions). On invalid input, returns HTTP 422 with an error message describing what is wrong.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "count": {
   "type": "number"
  },
  "expression": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cron-expression-validator-next-run-time-calculator-6c8ba4ab/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.jagent.dev](https://www.zero.xyz/host/api.jagent.dev/llms.txt)