How does this Aadhaar validator work?
The validator applies the three rules every Aadhaar number follows: it must be exactly 12 digits, it must not start with 0 or 1, and its last digit must be a correct Verhoeff check digit for the first 11. The Verhoeff algorithm is the same checksum UIDAI uses, and the check runs entirely in your browser.
After a result appears you can click Show the calculation to see each step of the checksum.
Is my Aadhaar data safe? Is it sent anywhere?
No data is sent anywhere. The validation code runs in JavaScript on your device; there is no server endpoint that receives numbers. The number is not stored in cookies, local storage or analytics. You can load the page, disconnect from the internet, and it still works.
The eye icon masks the number on screen while you type, for use in public places.
Does "valid" mean the Aadhaar number is real and active?
No. A valid result means the number is well-formed: it has the right shape and its check digit is mathematically correct. It does not mean UIDAI has issued that number, that it is active, or that it belongs to any particular person. Roughly one in ten random 12-digit strings passes the checksum by chance.
To confirm a number exists, use UIDAI's own Verify Aadhaar service. See how to check if an Aadhaar number is valid for all the official options.
Can an Aadhaar number start with 0 or 1?
No. UIDAI's numbering scheme never issues Aadhaar numbers beginning with 0 or 1. Every genuine number starts with a digit from 2 to 9. This is checked before the checksum.
Why does my real Aadhaar number show as invalid?
Almost always a typo. The Verhoeff algorithm is designed to catch exactly the mistakes people make: one wrong digit, or two adjacent digits swapped. Re-check each group of four against your card or e-Aadhaar. If you copied the number from a PDF, SMS or spreadsheet, make sure no digit was dropped, doubled or reformatted (Excel often turns long numbers into scientific notation).
What is the last digit of an Aadhaar number?
The 12th digit is a check digit computed from the first 11 using the Verhoeff algorithm. It carries no personal meaning; its only job is to detect typing errors. The Aadhaar number format guide explains all twelve positions.
What is an Aadhaar Virtual ID (VID) and can I validate it here?
A VID is a temporary 16-digit number mapped to your Aadhaar that you can share for authentication instead of the Aadhaar number itself. It uses the same Verhoeff checksum. Use the Virtual ID validator for 16-digit numbers.
What is a masked Aadhaar?
A masked Aadhaar shows only the last four digits (XXXX XXXX 7058). UIDAI lets you download one from the myAadhaar portal, and it is the recommended form to share when the full number is not required. Because the first eight digits are hidden, a masked Aadhaar cannot be checksum-validated — that is by design.
Why should I validate an Aadhaar number?
To catch typos before they cause problems. Common uses:
- Forms and onboarding: reject mistyped numbers instantly instead of after a failed e-KYC.
- Data cleanup: find bad entries in a spreadsheet with the bulk validator.
- Linking PAN and Aadhaar: confirm the number before submitting the request.
- Development and QA: unit-test your own validation with our test numbers.
Is this an official UIDAI service?
No. This is an independent tool that implements the publicly documented Verhoeff algorithm. It only checks the mathematical format of a number. It cannot verify whether a number is registered in the UIDAI database, authenticate anyone, or provide any official verification. For that, use the official UIDAI website or its authorised services.
What types of errors can the validator detect?
The Verhoeff algorithm detects 100% of single-digit errors and 100% of adjacent transpositions (12 → 21), and most twin errors (11 → 22), jump transpositions and phonetic errors (13 → 30). On top of that the validator checks length, the first-digit rule, non-numeric characters and repeated-digit placeholders like 999999999999.
What are the limitations of this validator?
It cannot verify that a number has been issued, that it belongs to a particular individual, or that it is currently active. It does not connect to any official database and cannot be used for official identity verification or KYC. For those, UIDAI's authentication and e-KYC services apply under the Aadhaar Act.
How do I validate Aadhaar numbers in Excel or Google Sheets?
There is no built-in spreadsheet function for the Verhoeff checksum. Copy the column, paste it into the bulk validator, and download the CSV report or copy the valid/invalid lists back. Before pasting, format the column as text so Excel does not convert numbers to scientific notation.
Can I use this validation in my own app or website?
Yes. The developer page has copy-paste implementations in JavaScript, TypeScript, Python, Java, C#, PHP, Go, Kotlin, Swift and Dart, plus the correct regex. You can also embed the validator with an iframe.
Are there test Aadhaar numbers I can use in development?
Yes. UIDAI publishes a handful of numbers for its sandbox (for example 999941057058), and our test numbers page lists them along with invalid cases for negative tests and a generator for random checksum-valid numbers. Never use real Aadhaar numbers in test systems.
Does the validator work offline?
Yes. Once a page has loaded, the site installs a small service worker that keeps the validators available without a connection. This is possible precisely because there is no server involved in validation.