What Is eSign? A Guide to Electronic Signing in India

eSign is a legally valid method of signing documents electronically using your Aadhaar identity, without needing a physical signature, printer, or stamp. In India, the most widely used form is Aadhaar eSign — a service that lets any Aadhaar holder sign a document by verifying their identity through a one-time password (OTP) sent to their registered mobile number.

This guide covers how eSign works, its legal standing under Indian law, and how it compares to a Digital Signature Certificate (DSC) and a traditional wet signature. For Aadhaar-based eSign in detail, including the full OTP flow and legal framework, see our dedicated post.

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How Aadhaar eSign Works: The OTP Flow

The process is straightforward and takes under two minutes:

1. Upload the document — The signing platform (called an Application Service Provider, or ASP) prepares the document for signing.
2. Enter your Aadhaar number — The system submits an e-KYC authentication request to UIDAI (Unique Identification Authority of India).
3. Receive an OTP — UIDAI sends a six-digit OTP to the mobile number linked to your Aadhaar.
4. Submit the OTP — Once you enter the OTP, UIDAI authenticates your identity and returns a digital signature that is affixed to the document.
5. Document is signed — The signed document contains a cryptographic seal that proves the identity of the signer and that the document has not been altered.

The entire flow runs over UIDAI's authentication infrastructure. Neither the ASP nor the signing platform ever handles your biometric data. Your private key is generated and used within UIDAI's Hardware Security Module (HSM) and is not stored anywhere after the signing event.

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Legal Validity of eSign in India

For a deep dive into the legal validity of eSign in India, including court admissibility and state-specific rules, see our legal guide.

eSign is legally valid under two primary instruments:

Information Technology Act, 2000 (IT Act) — Section 3A, inserted by the 2008 amendment, recognises electronic signatures as legally equivalent to handwritten signatures, provided the signature method is notified by the Central Government.

Controller of Certifying Authorities (CCA) Guidelines, 2015 — The CCA issued guidelines that formally notified Aadhaar-based eSign as an accepted electronic signature method. These guidelines define the role of ASPs, the responsibility of UIDAI, and the technical standards that signing platforms must meet.

Practically, this means that a rent agreement, an employment offer letter, an NDA, a loan application, or a vendor contract signed using Aadhaar eSign carries the same legal weight as a physical signature — unless the specific document type is excluded.

What cannot be signed using eSign? Certain documents require a DSC or a wet signature by law. These include:

• Wills and testamentary documents
• Power of attorney for immovable property transactions (in some states)
• Court filings under specific procedural rules
• Negotiable instruments like cheques (under the Negotiable Instruments Act, 1881)

For the vast majority of commercial and personal documents, eSign is sufficient.

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eSign vs DSC vs Wet Signature: A Comparison

Feature	Aadhaar eSign	Digital Signature Certificate (DSC)	Wet Signature
Legal basis	IT Act 2000, Section 3A; CCA 2015	IT Act 2000, Section 3	Indian Contract Act, 1872
Identity verification	UIDAI Aadhaar OTP / biometric	Issued by licensed CA (e.g., eMudhra, Sify)	Visual comparison
Hardware required	None	USB token (e-token)	Pen
Time to sign	Under 2 minutes	2–5 minutes (token insertion, PIN)	Minutes to days (courier)
Cost to signer	Usually absorbed by platform	₹1,000–₹3,000/year for DSC	Nil
Tamper detection	Yes (cryptographic hash)	Yes (cryptographic hash)	No
Works remotely	Yes	Only with physical token	Requires physical presence or courier
Best for	B2C contracts, HR, rental, banking	Company MCA filings, IT returns, tenders	Notarised documents, wills

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eSign vs Electronic Signature: What Is the Difference?

People often use "electronic signature" and "eSign" interchangeably, but there is a distinction.

An electronic signature is the broad category — any electronic sound, symbol, or process attached to a document with the intent to sign. This includes a typed name at the bottom of an email, a signature image pasted into a PDF, or a drawn signature on a touchscreen.

eSign (as used in India) specifically refers to the Aadhaar-based electronic signature service notified by the CCA. Because it is backed by UIDAI authentication, it carries a higher legal standing than a simple typed name or drawn signature.

For high-value contracts, regulated industries (banking, insurance, NBFCs), and anything that may need to be produced before a court or regulator, Aadhaar eSign is the appropriate choice over a basic electronic signature.

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Who Can Use eSign?

Any Indian resident with:

• A valid Aadhaar number
• A mobile number linked to their Aadhaar (for OTP delivery)

can use Aadhaar eSign. There is no additional registration required on the signer's side — no app to install, no account to create.

For businesses that want to send documents for eSign, they need to integrate with a licensed ASP or use a signing platform built on top of one. Platforms like SignSetu handle the ASP layer and provide a document workflow on top, so businesses do not need to build the UIDAI integration themselves.

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Common Use Cases for eSign in India

HR and Employment Offer letters, appointment letters, NDAs, and relieving letters are among the most common documents signed digitally. Large enterprises routinely process thousands of offer letters a month — printing and couriering is simply not viable at that scale.

Rental Agreements A landlord in Pune and a tenant relocating from Chennai can both sign the same rental agreement within minutes, without meeting in person. The agreement is legally valid as long as the appropriate stamp duty has been paid.

Banking and Lending Banks, NBFCs, and fintech companies use eSign for loan applications, account opening forms, and mandate registrations. The Reserve Bank of India has accepted Aadhaar-based e-KYC and eSign for several customer onboarding processes.

Government and Compliance Several state government portals and central government departments accept eSigned documents for applications, affidavits, and submissions.

Legal and Professional Services Law firms use eSign for engagement letters and retainers. Chartered accountants use it for client authorisations and engagement agreements.

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Security: How Safe Is eSign?

The security of Aadhaar eSign rests on three layers:

1. UIDAI's infrastructure — Authentication happens on UIDAI's servers, which are among the most audited systems in India. Biometric and OTP data is not accessible to the signing platform.
2. Cryptographic integrity — Once signed, the document contains a hash. Any modification to the document after signing invalidates the signature, making tampering detectable.
3. Audit trail — Every signing event generates a log with the signer's identity (masked Aadhaar), timestamp, IP address, and device information. This log is admissible as evidence under Section 65B of the Indian Evidence Act, 1872.

One limitation: OTP-based Aadhaar eSign is susceptible to SIM swap fraud if an attacker has access to both the victim's Aadhaar number and their phone. For very high-value transactions, biometric-based Aadhaar eSign (fingerprint or iris) provides stronger assurance.

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Conclusion: Is eSign the Right Choice for You?

eSign is the most practical way to sign documents digitally in India for the large majority of use cases. For a breakdown of free vs paid eSign options, see our cost comparison. It requires no hardware, no prior registration, and no technical knowledge from the signer. Its legal validity under the IT Act 2000 and CCA 2015 guidelines is well-established.

If you are a business that sends documents for signature — whether HR contracts, rental agreements, or financial forms — integrating with an eSign platform is straightforward. If you are an individual who needs to sign a document, all you need is your Aadhaar number and a linked mobile number.

For documents that require a DSC (MCA filings, income tax, government tenders), eSign is not a substitute. For a full eSign vs DSC comparison, including cost analysis and use-case breakdowns, see our detailed guide. For everything else, it is the faster, cheaper, and equally valid alternative.