How to eSign Documents Using Aadhaar OTP

eSign Any Document with Aadhaar OTP in 5 Minutes

You can eSign a PDF document using your Aadhaar number and a one-time password sent to your registered mobile. The process requires no USB token, no software installation, and no prior registration. All you need is your 12-digit Aadhaar number and a phone with the mobile number linked to your Aadhaar.

This guide walks through the exact steps, common mistakes to avoid, and what to do if something goes wrong.

Before You Start: Prerequisites Checklist

Make sure you have these ready:

• Aadhaar number — Your 12-digit Aadhaar or 16-digit Virtual ID (VID)
• Registered mobile — The mobile number linked to your Aadhaar must be active and with you
• Document to sign — A PDF file (most platforms accept PDF only; convert Word/image files to PDF first)
• Browser — Chrome, Firefox, or Edge (updated to the latest version)
• Stable internet — OTP delivery can fail on very slow connections

How to check if your mobile is linked to Aadhaar:

Visit myaadhaar.uidai.gov.in and use the "Verify Mobile/Email" service. Enter your Aadhaar number, request an OTP, and the system will confirm if your mobile number is linked.

If your mobile is not linked, visit any Aadhaar enrolment centre with your Aadhaar card and working mobile. The update takes about 15 minutes and is free of charge.

Step-by-Step: eSign Using Aadhaar OTP

Step 1: Upload Your Document

Go to your eSign platform. On SignSetu, for example, you click "Upload Document" and select your PDF file. Most platforms accept PDFs up to 10-25 MB.

If your document is in Word format, convert it to PDF first using Google Docs, Microsoft Word, or any free online converter. The document must be in PDF format for the digital signature to be embedded correctly.

Step 2: Add Signers

Enter the email addresses of everyone who needs to sign. You can add:

• Single signer — Just yourself
• Multiple signers — Add all parties in the order they should sign
• Sequential signing — Signer 2 receives the document only after Signer 1 completes

Each signer will receive an email notification with a link to sign.

Step 3: Configure Signature Placement (Optional)

Some platforms let you drag and drop signature fields onto specific locations in the document. This is useful for contracts where the signature needs to appear on a specific page or next to a particular clause.

If you skip this step, the signature is typically appended to the end of the document or applied as an invisible digital signature (the document looks the same but carries the cryptographic signature in its metadata).

Step 4: Initiate Signing

Click "Send for Signing" or "Sign Now" (depending on whether you are the signer or are sending to others).

When it is your turn to sign:

1. Click the signing link in your email
2. The document opens in your browser for review
3. Click "Sign with Aadhaar"
4. Enter your 12-digit Aadhaar number
5. Read and accept the consent statement (this authorises UIDAI to verify your identity)
6. Click "Send OTP"

Step 5: Enter OTP

UIDAI sends a 6-digit OTP to your registered mobile number. The OTP is valid for 10 minutes.

Enter the OTP and click "Verify" or "Submit."

Step 6: Download Signed Document

Once the OTP is verified:

• A digital certificate is generated by the CCA-licensed eSign service provider
• The certificate is applied to the document
• The signed PDF is available for download immediately

If you need to add a digital signature to your PDF using a DSC or other tools, see our PDF signing guide.

The signed document includes:

• A digital signature that is cryptographically bound to the document
• Signer identity verification via Aadhaar
• A timestamp showing exactly when the signature was applied
• Tamper-evident protection — any modification after signing invalidates the signature

Troubleshooting Common Issues

OTP not received

Possible Cause	Solution
Mobile not linked to Aadhaar	Visit Aadhaar enrolment centre to link mobile
Network delay	Wait 60 seconds, then click "Resend OTP"
DND active	eSign OTPs are transactional, not promotional. DND should not block them. Contact your telecom provider if blocked
UIDAI server downtime	Check uidai.gov.in for maintenance notices. Try again in 30 minutes

"Authentication failed" error

This usually means one of:

• You entered an incorrect Aadhaar number (re-check all 12 digits)
• Your Aadhaar is deactivated (contact UIDAI helpline 1947)
• You entered the wrong OTP (request a new one)

Document shows "Signature invalid" after signing

Check if you are using a PDF reader that trusts CCA root certificates. Install the CCA root certificates from cca.gov.in into Adobe Reader. The signature is valid — your reader just does not recognise the Indian CA.

Security of Aadhaar eSign

A reasonable question: is it safe to enter your Aadhaar number on a signing platform?

Here is how the security works:

1. Your Aadhaar number is not stored by the application. It is passed to the eSign service provider for one-time authentication
2. UIDAI only sends a yes/no response — no biometric data, no demographic data is shared with the application
3. The OTP is generated by UIDAI, not by the signing platform. The platform cannot intercept or generate OTPs
4. Short-lived certificates — The digital certificate generated for your signature expires in 30 minutes. It cannot be reused
5. All CCA-licensed ESPs undergo regular security audits mandated by the government

The security model is the same one used by banks, insurance companies, and government departments for Aadhaar authentication. Over 2 crore Aadhaar authentications happen every day across India.

Cost of Aadhaar eSign

Aadhaar eSign pricing depends on the platform:

Usage	Typical Cost
Individual (1-10 signs/month)	Rs 10-50 per signature or free tier
Small business (50-200 signs/month)	Rs 5-15 per signature
Enterprise (1000+ signs/month)	Rs 4-8 per signature (volume discount)

Compare this with the cost of physical signing: printing, couriering, collecting, scanning, and storing physical documents. For a business sending 100 agreements per month by courier at Rs 50-80 per shipment, that is Rs 5,000-8,000 monthly just on logistics — before accounting for the 3-7 day delay in getting signatures back.

When Aadhaar eSign Is Not the Right Choice

To learn more about Aadhaar eSign — including its legal framework and common use cases — see our full guide.

Aadhaar eSign works for most document signing needs, but there are exceptions:

• MCA filings (company incorporation, annual returns) — These specifically require a Class 3 DSC
• GST registration — Requires DSC for companies and LLPs
• Patent and trademark filings — IP office requires DSC
• Property registration — Most states still require physical presence for sale deeds

For everything else — employment contracts, vendor agreements, NDAs, consent forms, loan documents, insurance policies — Aadhaar eSign is the faster and cheaper option.

Start Signing

Once signed, remember to verify your signed document to confirm the signature is valid before sharing it.

The gap between knowing about Aadhaar eSign and actually using it is usually just one signed document. Pick a low-stakes document — a team NDA or an internal approval form — and run it through the process. Once you see how fast it is, physical signatures feel like sending a fax.