Aadhaar Checksum Validator

What this tool does

Aadhaar Checksum Validator checks a 12-digit Aadhaar-format number against the Verhoeff checksum algorithm UIDAI uses for its final digit. This is a structural self-consistency check only, performed entirely in your browser with nothing transmitted anywhere, and it cannot and does not confirm a number is genuinely issued, active or belongs to any real person.

UIDAI, the issuer of India’s Aadhaar numbers, builds the Verhoeff checksum algorithm into the final digit of every genuine Aadhaar number, an error-detecting scheme chosen specifically because it catches a wider range of common typing mistakes (including adjacent transpositions) than a simpler checksum like Luhn.

This tool checks any 12-digit, Aadhaar-formatted number against that same Verhoeff algorithm. It is important to be clear about what this does and doesn’t prove: it confirms mathematical self-consistency only, never that a number is genuinely issued, active, or belongs to a real person — UIDAI deliberately does not offer any public way to verify real issuance, precisely to protect holders’ privacy.

How to use Aadhaar Checksum Validator

1. Enter the 12-digit number.
2. Confirm it doesn’t start with 0 or 1 (real Aadhaar numbers never do).
3. Review the Verhoeff checksum result.
4. Treat "valid" as a format check only, never as proof of real issuance.

Tips for better results

• A real Aadhaar number never starts with 0 or 1; this tool rejects such input immediately as structurally invalid before even running the checksum.
• Treat a "valid" result strictly as "correctly formatted", never as confirmation of a real, issued, active Aadhaar number; there is no legitimate public API or tool, including this one, that can confirm genuine issuance.
• Nothing entered here is ever transmitted, logged or stored anywhere; the Verhoeff calculation runs entirely within your own browser session.
• The number is shown back to you masked (only the last 4 digits visible) as a precaution, consistent with how Aadhaar numbers are conventionally displayed elsewhere.

Common use cases

• Checking that an Aadhaar-format number was typed without an obvious digit error before using it in a form.
• Learning how the Verhoeff checksum algorithm works as a more robust alternative to simpler schemes like Luhn.
• Validating Aadhaar-format input structurally in a KYC or onboarding flow, as a first-pass typo check only.
• Understanding the limits of what a format check can and can’t confirm about a sensitive government identifier.

Common mistakes to avoid

• Treating a "valid" result as confirmation of a real, active Aadhaar number; this is explicitly a format self-consistency check only — UIDAI provides no legitimate public way to verify actual issuance, and this tool makes no such claim.
• Entering a real Aadhaar number into any third-party tool unnecessarily; even though this one processes everything locally and transmits nothing, minimising where a sensitive identifier is typed at all is good practice.
• Assuming a number starting with 0 or 1 might just be an edge case; real Aadhaar numbers are guaranteed to never start with those digits, so such input is rejected immediately as invalid.