How to electronically sign a PDF

What is an electronic signature?

An electronic signature (e-signature) is any electronic symbol, sound, or process attached to or logically associated with a document and executed or adopted by a person with the intent to sign. In practice, this means a drawn, typed, or uploaded image of a signature placed on a digital document.

The defining element is intent: the signer must choose to sign and must understand what they are signing. The form the signature takes — a drawn scrawl, a typed name in cursive font, or a photo of a pen-on-paper signature — is secondary to that intent. This is why the law in most countries does not prescribe a specific form for electronic signatures but focuses instead on the evidentiary framework around them.

Electronic signature vs digital signature

The two terms are often used interchangeably, but they are not the same thing. An electronic signature is any electronic mark indicating intent to sign — a drawn, typed, or image signature placed on a document. This is what the vast majority of agreements require.

A digital signature is a specific, cryptographic technology that uses a Public Key Infrastructure (PKI) certificate issued by a trusted Certificate Authority to mathematically bind a signer's identity to a file. The cryptographic binding makes tampering detectable: if a single character of the document changes after signing, the digital signature becomes invalid. Digital signatures correspond to the EU eIDAS Regulation's "Advanced Electronic Signature" (AES) and "Qualified Electronic Signature" (QES) tiers. QES, the highest tier, requires a qualified trust service provider and carries the same legal weight as a handwritten signature across all EU member states.

For everyday contracts, NDAs, offer letters, rental agreements, and consent forms, an electronic signature is what is needed and what is legally sufficient. Certificate-based digital signatures are required only in specialized contexts — some government filings, regulated financial instruments, and cross-border legal proceedings with specific authentication requirements.

Are electronic signatures legally binding?

Yes, for most documents. In the United States, the Electronic Signatures in Global and National Commerce Act (ESIGN Act, 2000) gives electronic signatures the same legal effect as handwritten ones. The Uniform Electronic Transactions Act (UETA), adopted by 47 states plus DC and the US Virgin Islands, provides equivalent recognition at the state level. Both require that the parties intend to sign, consent to transact electronically, and that the signed record be retained in a form that is accurately reproducible.

In the European Union, the eIDAS Regulation (Regulation (EU) No 910/2014) establishes three tiers of electronic signature. A Simple Electronic Signature (SES) — the tier that covers drawn, typed, or uploaded signatures — is legally valid and admissible as evidence across the EU; its weight in court depends on context and the ability to prove authenticity. Most other major economies, including the UK, Canada, Australia, and Japan, have enacted equivalent laws.

What makes an e-signature hold up in a dispute is the surrounding evidence of intent and consent: the signer chose to sign, understood what they were signing, and the document was not altered afterward. Keeping the final signed PDF and any surrounding email or transaction record is usually sufficient for standard business agreements.

When you might still need a wet or digital signature

A defined set of document types are excluded from the ESIGN Act and UETA, or carry their own formal requirements that a simple e-signature does not satisfy. These include: wills, codicils, and testamentary trusts (in most states); certain real-estate deeds and mortgages that must be recorded with a county recorder; some court filings, pleadings, and sworn affidavits; family law documents such as adoption decrees and certain divorce instruments; and specific financial instruments governed by Articles of the Uniform Commercial Code outside Articles 2 and 2A.

Some of these document types require notarization — a notary's physical or remote online seal and signature alongside the signer's. Over 45 US states now permit Remote Online Notarization (RON), which lets the notarization happen via a video call with an authorized notary, so even this requirement can often be satisfied without a physical meeting.

If you are unsure whether a specific document requires more than an electronic signature, the safest approach is to ask the requesting party or consult a qualified attorney. For standard business documents — contracts, NDAs, employment offers, consent forms — a simple e-signature is the norm and is legally sufficient.

How to create an electronic signature that stands up

The legal validity of an e-signature depends less on how it looks and more on the context surrounding the signing. For a signed document to be defensible, you should: sign the correct, final version of the document (not a draft); retain the signed PDF in a secure, accessible location; keep any email or message thread that demonstrates you received the document and chose to sign it; and ensure that the document was not altered after signing.

A browser-based signer that processes the document locally and returns a flattened PDF satisfies the technical side: the signature is embedded and cannot be moved or deleted after the fact. The surrounding record — the email exchange, the date and time of signing — is what provides the evidentiary context.

The eIDAS tiers and when each applies

For readers operating in or with parties in the EU, understanding the eIDAS tiers helps clarify when a simple e-signature suffices and when a higher level is needed.

• >Simple Electronic Signature (SES): any electronic mark indicating intent — drawn, typed, or uploaded signature. Valid for the vast majority of commercial agreements. No identity verification required.
• >Advanced Electronic Signature (AES): uniquely linked to the signatory, capable of identifying them, created using data under their sole control, and linked to the document in a way that detects changes. Used for higher-value contracts where identity assurance matters.
• >Qualified Electronic Signature (QES): the highest tier, legally equivalent to a handwritten signature across all EU member states. Requires a qualified certificate from a qualified trust service provider and a qualified signature creation device. Used for regulated transactions, government filings, and cross-border instruments.

Keeping your signed document secure

After downloading your signed PDF, store it in a location you control and back it up. For important agreements, this might mean your own secure cloud storage with access controls (iCloud Drive with end-to-end encryption, for example) or a local drive with regular backup.

Do not rely on email as the only storage for signed contracts — email inboxes can be lost or compromised, and finding a specific attachment years later is not guaranteed. A dedicated folder for signed agreements, named clearly with the counterparty and date, is a simple organizational practice that makes retrieval straightforward when you need it.