# Cn resident id parse

`cn-resident-id-parse` · version 1.0.0 · Identifiers & check digits · free, no key needed

Parse an 18-digit (or legacy 15-digit) Chinese resident ID: region code, birth date, sex and GB 11643-1999 check digit.

**Use when you need to: parse a chinese id card number · validate a china resident identity card number · check digit for a PRC id number.**

## Decide before calling

Read the [versioned contract](/v1/tools/cn-resident-id-parse/versions/1.0.0) and the supported scope below. Reuse `cn-resident-id-parse@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `cn-resident-id-parse@1.0.0` for parse a chinese id card number. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- parse a chinese id card number
- validate a china resident identity card number
- check digit for a PRC id number
- extract birth date from chinese national id
- convert 15 digit chinese id to 18 digit
- GB 11643 id number checksum
- 身份证号码校验

## Not supported

- looking up the administrative region name for the 6-digit region code (no GB/T 2260 lookup or region-name data)
- validating a national ID from any country other than China
- accepting a lowercase x in the 18th position or any whitespace/hyphen formatting

## Behavior

- id must be exactly 15 ASCII digits (legacy form) or exactly 17 ASCII digits followed by a digit or uppercase X (18-digit form); anything else throws invalid_input. No trimming, case folding or separators.
- 15-digit input is upgraded to 17 digits by inserting '19' after the 6-digit region code (this tool assumes the 1900s century, since the 15-digit form predates the 2000s); 18-digit input's first 17 characters are used as-is.
- check_digit is always the GB 11643-1999 weighted mod-11 computation over the 17-digit payload (weights 7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2, remainder table 0..10 -> 1,0,X,9,8,7,6,5,4,3,2), independent of whether it matches the supplied 18th character.
- id18 preserves the original 18th character when one was supplied (even when it disagrees with check_digit); for 15-digit input, id18 uses the freshly computed check_digit, so a 15-digit input can never produce checksum_mismatch.
- birth_date is validated as a real proleptic Gregorian calendar date using the encoded 4-digit year (leap years: divisible by 4 and (not divisible by 100 or divisible by 400)); an invalid date reports birth_date: null and takes precedence over a checksum mismatch.
- sex is derived from the 17th character of the 17-digit payload (the last digit of the 3-digit sequence code): odd is male, even is female; this is always computed, regardless of date or checksum validity.
- region_code is the payload's first 6 characters returned unchanged; no administrative-division lookup is performed.
- Pure integer arithmetic and a fixed calendar rule; no locale, clock, or randomness; identical output across runs for the same input.

## Input

- `id` (string, required): min length 15; max length 18; pattern `^(\d{15}|\d{17}[0-9X])$`

## Output

- `valid` (boolean, required)
- `reason` (one of null, "invalid_birth_date", "checksum_mismatch", required)
- `region_code` (string, required): pattern `^\d{6}$`
- `birth_date` (string or null, required): pattern `^\d{4}-\d{2}-\d{2}$`
- `sex` (one of "male", "female", required)
- `check_digit` (string, required): pattern `^[0-9X]$`
- `id18` (string, required): pattern `^\d{17}[0-9X]$`

## Limits

- max input bytes: 18

## Example

Request input:

```json
{
  "id": "11010519491231002X"
}
```

Response:

```json
{
  "result": {
    "valid": true,
    "reason": null,
    "region_code": "110105",
    "birth_date": "1949-12-31",
    "sex": "female",
    "check_digit": "X",
    "id18": "11010519491231002X"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "cn-resident-id-parse",
  "version": "1.0.0",
  "input": {
    "id": "11010519491231002X"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/cn-resident-id-parse/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"id":"11010519491231002X"}'
```

The machine-readable contract is at [/v1/tools/cn-resident-id-parse/versions/1.0.0](/v1/tools/cn-resident-id-parse/versions/1.0.0).

### CLI

```sh
node cli.mjs run cn-resident-id-parse 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

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