README

Offline validation for Turkish citizen numbers (T.C. Kimlik No). Zero dependencies, a single static method, and no network access — the number is checked against the official checksum rules.

Requirements

PHP 8.1 or higher. Nothing else.

Installation

composer require x-adam/tr-citizen-number-validation

Usage

use XAdam\TrCitizenNumberValidation;

TrCitizenNumberValidation::validate(10000000146);   // true
TrCitizenNumberValidation::validate('10000000146'); // true
TrCitizenNumberValidation::validate('12345678901'); // false

Both int and string are accepted, so values coming straight from a request need no casting or pre-filtering. Anything that is not a well-formed citizen number — letters, empty strings, surrounding whitespace, wrong length — returns false instead of throwing:

TrCitizenNumberValidation::validate('not a number'); // false
TrCitizenNumberValidation::validate('');             // false
TrCitizenNumberValidation::validate('1709281905');   // false (10 digits)

What it checks

A Turkish citizen number is 11 digits long and carries two check digits:

Rule	Description
Length and range	Exactly 11 digits, the first one cannot be `0`
10th digit	`((d1 + d3 + d5 + d7 + d9) × 7 − (d2 + d4 + d6 + d8)) mod 10`
11th digit	`(d1 + … + d10) mod 10`

Because the 11th digit is always the result of 8 × (d1 + d3 + d5 + d7 + d9) mod 10, every valid number ends with an even digit — the library rejects odd endings up front.

What it does not check

This library answers "is this a well-formed citizen number?", not "does this number belong to this person?". The latter requires querying the Identity Sharing System (KPS) of the Turkish Directorate of Population and Citizenship Affairs; the formerly public NVİ endpoint was shut down on 30 September 2025, and verification against official records is now only available to institutions with a KPS membership.

Use this library to reject malformed input early — before storing it, or before paying for a lookup.

Laravel

For a ready-made tr_citizen_number validation rule, see x-laravel/validation-tr-citizen-number-extend, which wraps this library.

Testing

composer install
composer test
composer analyse

The suite covers the documented rules, malformed input, generated valid numbers, and numbers whose intermediate checksum is negative. CI runs it on PHP 8.1 through 8.5, along with PHPStan at its highest level.

License

Open source software licensed under the MIT license.

x-adam / tr-citizen-number-validation

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