Use Kitbench from AI (MCP)

AI assistants such as Claude can call Kitbench calculators. They return exactly the same answers as the tools on this site, including things AI often gets wrong: Japanese character counts, business days with Japanese holidays and Japanese era dates. Free, no sign-up.

Endpoint URL：https://kitbench.net/mcp

Tools (7)

• count_characters — Character count (Japanese-aware, manuscript paper, bytes)
• days_between — Days between dates, business days (Japanese holidays)
• add_days — Date after N days or N business days
• calculate_age — Age (also Japanese counting and zodiac)
• convert_japanese_era — Western year ⇄ Japanese era (wareki)
• consumption_tax — Japanese consumption tax (10% / 8%, rounding)
• convert_units — Unit conversion

Connect to Claude

1. Open claude.ai and go to Customize > Connectors
2. Click “+ Add”, then “Add custom connector”
3. Enter the name “KitBench” and the endpoint URL below, then click “Continue”
4. Choose “No sign in” for authentication and click “Add”
5. In a chat, click “+” at the lower left, open “Connectors” and turn KitBench on

Free plans can add one custom connector (per Anthropic’s help center). On Team and Enterprise plans, an organization owner adds it.

Example requests

• “Count the characters in this Japanese text, excluding spaces. How many sheets of manuscript paper is it?”
  count_characters returns the count as people see it (an emoji is 1), the count without spaces and the manuscript-paper sheets.
• “How many business days in Japan are there from October 8 to December 25, 2026?”
  days_between returns business days counted with the Japanese Cabinet Office holiday list.
• “Someone was born on Showa 63, May 3. How old are they today?”
  convert_japanese_era and calculate_age convert the era date and return the age.

Public API

The same calculations are available as a plain API. Open it without tool= to get the list of tools and arguments. Send long text with POST.

https://kitbench.net/kb-api/v1.php
https://kitbench.net/kb-api/v1.php?tool=days_between&start_date=2026-10-08&end_date=2026-12-25

Price, limits and data

• Free, no sign-up
• Up to 300 requests per 10 minutes from the same address (wait a moment and retry if you hit it)
• Text and dates are used only to return the answer and are not stored (see the privacy policy)

Privacy policy

Contact

If something doesn’t work or you’d like another tool, use our contact page.