CRN0

CRN0 for AI agents

Let your assistant convert cron schedules between timezones with the same engine as this site. It's free and needs no API key.

MCP server

Streamable HTTP, no auth.

https://crn0.com/mcp

Claude Code

claude mcp add --transport http crn0 https://crn0.com/mcp

Claude, ChatGPT and other apps

Add a custom connector and paste the URL above.

Cursor, Windsurf, VS Code and other config-based clients

{
  "mcpServers": {
    "crn0": {
      "type": "http",
      "url": "https://crn0.com/mcp"
    }
  }
}

Tools

convert_cron
Convert a cron expression from one timezone to another so it fires at the same real-world instants. Returns the converted cron line(s), plain-English descriptions, offsets, warnings (day shifts, multi-line results, DST) and the next run times in both zones.
describe_cron
Validate a cron expression and explain it in plain English, with the expanded values of each field.
next_cron_runs
List the next run times of a cron expression evaluated in a given timezone (DST-aware), in UTC and local wall time.
search_timezones
Look up IANA timezone ids and current UTC offsets by city, country, abbreviation or IANA name.

JSON API

GET with query params or POST JSON. CORS is open.

curl 'https://crn0.com/api/convert?cron=0+9+*+*+1-5&from=Australia/Sydney&to=UTC'
  • /api/convert: cron, from, to, at?, count?
  • /api/describe: cron
  • /api/next-runs: cron, timezone?, count?, from?
  • /api/timezones: query, limit?

Full schema in openapi.json.

Docs for language models