NIP, REGON and PESEL Validator

Fast, accurate and free online nip regon pesel validator tool running directly in your browser.

Secure (SSL)

Client-Side Processing

100% Free

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Instructions

1

Enter data
Enter content, paste text or load a file from disk.
2

Click the button
The tool will immediately process your data in the browser.
3

Get the result
Copy the finished text or save the file to your device.

                                                function runTool() {

                                                  return "Result ready in 0.1s";

                                                }

NIP REGON PESEL validator

Check the correctness of Polish identification numbers and read the detailed information encoded in them.

Input

Identification number

Number type

Waiting for a number

Enter the ID number in the adjacent panel to see the analysis result.

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NIP, REGON and PESEL validator online - check the number in a second

An incorrect NIP number on the invoice, a typo in the REGON number in the contract or the PESEL number entered with a changed digit can cause an avalanche of problems: from rejected documents, through chaos in the customer database, to costly corrections in the accounting system. This NIP/REGON/PESEL validator helps you quickly check whether the number isformally correct(length + checksum), and in the case of PESEL - additionally extracts useful information from it, such asdate of birth, gender, age, day of the week of birth i century.

Automatic type detection Checksum validation Reading data from PESEL Clear reasons for errors Quick, without unnecessary steps

What is the NIP/REGON/PESEL validator used for?

The tool was created for everyday work with data: in companies, accounting offices, administration departments, e-commerce, in applications that accept data from users, as well as in private situations when you want to make sure that the number has not been entered incorrectly. The validator works quickly and clearly: you enter the number, select the type (or leave "Auto"), and you get the result immediately.

Most common applications

Checking the contractor's NIP number before issuing an invoice or correction.
Checking the REGON number in registration documents and contracts.
PESEL validation in forms (e.g. recruitment, subscriptions, insurance).
Data verification when importing from CSV/XLSX (detection of incorrect records).
Organizing the customer database: removing typos and incorrect entries.

What we check and what we don't

This validator verifies themathematical correctness ofnumbers (length and checksum), and in the case of PESEL, additionally analyzes the encoded date. This is important because a correct checksum significantly reduces the risk of typos.

Note:the validator does not confirm whether the company actually exists in the CEIDG/KRS databases or whether the number belongs to a specific person. It is a tool for formal validation and analysis of the number structure.

How does "Auto" mode and number type detection work?

If you are not sure whether you are pasting the NIP, REGON or PESEL number, the "Auto" mode recognizes the type by the number of digits (after removing spaces, dashes and other characters). The rule is simple:

Type	Length	What we validate	Additional info
NIP	10 digits	Checksum (modulo 11)	Format XXX-XXX-XX-XX
REGON	9 or 14 digits	Checksum (modulo 11, 10→0)	Variant 9/14 (entity / entity)
PESEL	11 digits	Sum control + date correctness	Date of birth, gender, age, day of the week, century, zodiac

In most cases, automation is the most convenient because you just need to paste the number and click "Check". Manual selection is worth considering when you test data in series, enforce a specific type or want to quickly compare results (e.g. check how the tool will behave with a number of unusual length).

NIP validation – what does "checksum" mean and how to read the result?

The NIP number consists of 10 digits. Verification involves calculating the checksu