CronSpell MCP Server

by workers-mike-tusa-cronspell Your server? Claim it

answering

CronSpell is answering right now. Last checked 7 min ago. It exposes 4 tools.

Validate and explain cron expressions; list next/previous run times in any time zone, DST-aware.

Uptime history 68 hours of history

68 hours agonow

100.0%

Uptime 24h

91 of 91 checks

Tools

read from the server

133 ms

Response time

average over 24h

open, no key

Access

streamable-http

Nothing serious here today

Today is the operative word: we check CronSpell every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 7 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add cronspell --transport http https://cronspell.mike-tusa.workers.dev/mcp

Settings → Connectors → Add custom connector, then paste this address

https://cronspell.mike-tusa.workers.dev/mcp

~/.codex/config.toml

[mcp_servers.cronspell]
url = "https://cronspell.mike-tusa.workers.dev/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "cronspell": {
      "url": "https://cronspell.mike-tusa.workers.dev/mcp"
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "cronspell": {
      "type": "http",
      "url": "https://cronspell.mike-tusa.workers.dev/mcp"
    }
  }
}

Available tools 4

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

cron

cron_runs_between

List every run of a cron expression between start and end (both inclusive) in an IANA time zone, DST-aware, oldest first. Default limit 20, max 100; truncated is true when there are more. Read-only. Same engine as GET /api/between.

explain

explain_cron

Explain a cron expression in plain English, e.g. "0 9 * * 1-5" → "At 09:00, on Monday through Friday." Also returns notes on cron rules that often surprise people (day-of-month OR day-of-week, seconds field, shorthand expansion). Invalid expressions return isError with the reason. Read-only. Same engine as GET /api/explain.

next_cron_runs

List the next (or, with direction "previous", the most recent past) run times of a cron expression in an IANA time zone, DST-aware. Each run has the local time with its UTC offset, the UTC time, unix seconds and weekday. Default 5 runs, max 20; searches up to 50 years. Read-only. Same engine as GET /api/next and GET /api/previous.

validate

validate_cron

Check whether a cron expression is valid. Returns valid true with the expanded values of every field (minute, hour, day of month, month, day of week, and seconds for 6-field expressions), or valid false with an error code, the field at fault and a message. Detects schedules that can never run (e.g. February 30). Read-only. Same engine as GET /api/validate.

Endpoints

URL	Transport	State	Latency	Checked
https://cronspell.mike-tusa.workers.dev/mcp	streamable-http	answering	1339 ms	7 min ago

Alternatives to CronSpell

same job, measured the same way

Cron Tools

by basitalisandhu

Parse, explain and validate 5-field cron expressions and list upcoming runs in a time zone.

local only

Cron Explainer

by idoazacalls

Cron expression parser: explains any cron + returns next N fire times. Timezone-aware.

1 tools answering

Cron Translator

by crontoenglish

Explain cron expressions in English, list next run times, and catch scheduling gotchas.

3 tools answering

Cron Forge MCP

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Build, explain, and validate cron expressions

32 installs/wk local only

Regex MCP

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Test, describe, and validate regular expressions locally. No network and no key.

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Cron MCP

by mrfentmen

Parse, describe, and compute next runs for cron expressions locally. No network and no key.

788 installs/wk local only

Lakelogic MCP

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Validate, lint, test-run and explain Open Lakehouse Contracts with LakeLogic, from any AI assistant.

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Regex Lab MCP

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Test, explain, and generate regular expressions

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CronSpell — questions

Answers built from our own checks of this server.

What can CronSpell do?

It exposes 4 tools, read directly from the server on our last check. Among them: cron_runs_between, explain_cron, next_cron_runs, validate_cron. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →

Is CronSpell working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 133 ms. The bar chart above shows every period we have measured.

How do I connect CronSpell?

Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.

Does CronSpell need an API key?

No. CronSpell completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 4 of them are readable on this page. This is what we observed, not what the docs claim.

How fast is CronSpell?

It answers our handshake in 133 ms on average, which is faster than 91% of all working MCP servers we measure. That puts it in the quick quarter of the ecosystem. The comparison comes from our own checks across the whole registry, every 15 minutes.