Castov Cron Engine vs Crontab.guru — IANA Timezone & MCP Support
Compare Castov's timezone-aware Cron Expression Parser (Web, CLI `npx castov cron`, and MCP tool `castov_cron`) against Crontab.guru for Kubernetes, GitHub Actions, and cloud schedulers.
Crontab.guru is a classic minimalist web tool for 5-field cron syntax. Castov goes further by adding explicit IANA timezone simulation (`America/New_York`, `UTC`, `Asia/Tokyo`), next-5 execution ISO-8601 timestamps, terminal CLI execution (`npx castov cron`), and native MCP agent verification (`castov_cron`).
Feature-by-Feature Comparison: Castov vs. Crontab.guru
| Capability / Dimension | Castov (v1.4.0) | Crontab.guru |
|---|---|---|
| IANA Timezone Execution Preview | Yes — preview next 5 exact run times in any IANA timezone with DST awareness | Local browser time only (no IANA timezone selector) |
| CLI & CI/CD Validation (`npx castov cron`) | Yes — validate cron strings in scripts and CI pipelines with `--json` output | Browser-only website |
| AI Agent MCP Verification (`castov_cron`) | Yes — prevents LLM cron syntax hallucinations via deterministic MCP tool | None |
| Instant 5-Field Human-Readable Translation | Yes — instant human summary + next 5 ISO-8601 execution timestamps | Yes — instant human summary + next execution time |
When to Choose Castov
- You are scheduling GitHub Actions (`UTC`), Kubernetes `CronJob`s, or Vercel Cron jobs and need to verify exact run times across `UTC` and local IANA timezones.
- You want your AI assistant (Claude/Cursor) to verify cron expressions deterministically using `castov_cron` instead of guessing field order.
- You need a CLI tool (`npx castov cron "0 9 * * 1-5"`) inside your terminal.
When to Keep Crontab.guru
- You only need a quick browser bookmark for basic 5-field Linux crontab syntax without timezone conversion or CLI/MCP integration.
How to Run Castov in 60 Seconds (Zero Config)
Test Cron Schedules in Terminal
Run `npx castov cron "*/15 * * * *"` to get a human-readable explanation and the next 5 UTC execution timestamps.
Verify Timezone Offsets
Pair `castov_cron` with `castov_timezone` in your MCP-enabled IDE to verify how Daylight Saving Time (DST) affects scheduled jobs.
Explore Interactive Cron Reference Pages
Use `https://www.castov.com/cron` and `https://www.castov.com/cron-expression-generator` to build and share schedules.
Need Zero-Knowledge .env Secret Sync Across Your Engineering Team?
Explore Castov Env Vault for client-side AES-256-GCM encrypted environment sharing, or sponsor this engineering hub.