Czech Birth Number Validation

Check a Czech birth number (rodné číslo): format, embedded date of birth, sex encoding and, for 10-digit numbers from 1954 on, the mod-11 checksum.

cz-birth-number-validate

Example

Input

{
  "birth_number": "750519/0110"
}

Answer

{
  "input": "750519/0110",
  "gender": "male",
  "reason": "Birth number is well-formed.",
  "is_valid": true,
  "birth_day": 19,
  "birth_year": 1975,
  "date_valid": true,
  "normalized": "7505190110",
  "birth_month": 5,
  "checksum_ok": true,
  "has_check_digit": true
}

Inputs

Field	Type	Required	What it is
`birth_number`	string	Yes	Czech rodné číslo (9 digits pre-1954 or 10 digits post-1954, optional slash/hyphen)

Output fields

How reliably each field appears in a successful answer.

Field	Type	Appears
`input`	string	Always (present in every successful answer)
`gender`	string	Always (present in every successful answer)
`reason`	string	Always (present in every successful answer)
`is_valid`	boolean	Always (present in every successful answer)
`birth_day`	integer	Always (present in every successful answer)
`birth_year`	integer	Always (present in every successful answer)
`date_valid`	boolean	Always (present in every successful answer)
`normalized`	string	Always (present in every successful answer)
`birth_month`	integer	Always (present in every successful answer)
`checksum_ok`	boolean	Always (present in every successful answer)
`has_check_digit`	boolean	Always (present in every successful answer)

How to call it

The same tool through each route. MCP clients reach it through Strale’s server at https://api.strale.io/mcp; the call below is what the agent sends.

# Needs an API key. max_price_cents caps what this call may cost.
curl -X POST https://api.strale.io/v1/do \
  -H "Authorization: Bearer $STRALE_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
    "capability_slug": "cz-birth-number-validate",
    "inputs": {
      "birth_number": "750519/0110"
    },
    "max_price_cents": 2
  }'

{
  "tool": "strale_execute",
  "arguments": {
    "slug": "cz-birth-number-validate",
    "inputs": {
      "birth_number": "750519/0110"
    },
    "max_price_cents": 2
  }
}

import { Strale } from "straleio";

const strale = new Strale({ apiKey: process.env.STRALE_API_KEY! });
const result = await strale.do({
  capability_slug: "cz-birth-number-validate",
  inputs: {
    "birth_number": "750519/0110"
  },
  max_price_cents: 2,
});

import os
from straleio import Strale, DoRequest

strale = Strale(api_key=os.environ["STRALE_API_KEY"])
result = strale.do(DoRequest(
    capability_slug="cz-birth-number-validate",
    inputs={
        "birth_number": "750519/0110",
    },
    max_price_cents=2,
))

Limitations

Pre-1954 numbers have no checksum
9-digit birth numbers issued before 1954 have no mod-11 check digit. Format and date are validated but checksum_ok is always true.
Personal data handling — treat as sensitive
Rodné číslo is a Czech national identifier subject to GDPR. Callers should not log or persist these values beyond the immediate validation use case.