The term "digital signature" is used loosely to mean several different things, and the confusion between them can lead people to either use an inadequate method for a high-stakes document or over-engineer a solution for a simple form. This guide distinguishes between the main approaches, explains when each is appropriate, and shows the fastest way to add a signature to a PDF for everyday use.
Three types of PDF signature
Understanding the distinctions here avoids the most common mistake in PDF signing.
An electronic signature in the broad sense is anything that identifies you as the person who signed the document. This includes a drawn signature, a typed name in a cursive font, an image of your handwritten signature, or a checkbox next to a statement of agreement. The defining feature is that it is a representation of your intent to sign, not a cryptographic proof.
A digital signature in the technical sense is a cryptographic operation. It uses a private key associated with a verified identity to create a mathematical proof that the document content has not changed since you signed it and that the signature came from your verified certificate. This requires a digital certificate issued by a certificate authority. It is the approach used in regulated industries, legal proceedings, and contexts where the identity and integrity of the signer must be verifiable by a third party.
A qualified electronic signature is the highest standard, defined in eIDAS regulation in the EU and equivalent frameworks elsewhere. It requires identity verification and a qualified certificate from an accredited provider. These are mainly relevant for notarial acts, regulated financial transactions, and government filings.
For the vast majority of everyday document signing, employment contracts, service agreements, consent forms, NDAs, offer letters, lease agreements, a simple electronic signature is legally sufficient in the UK under the Electronic Communications Act 2000 and its successor legislation.
How to add a drawn signature to a PDF
PDFWhisk's signing tool lets you add a signature to any PDF in your browser with no upload and no account. The signature options are draw, type, or upload an image of your signature.
For drawn signatures, open the tool on a touchscreen, a phone, tablet, or touchscreen laptop, and draw your signature with your finger or stylus. On a desktop without a touchscreen you can draw with the mouse, though results are less natural. Once drawn, drag the signature into position on the page and resize using the corner handles. The signature is embedded permanently in the PDF, not as an overlay that can be removed with a basic edit.
Signing on your phone
Signing on a touchscreen phone is often the most natural way to get a drawn signature into a document. Open PDFWhisk's signing tool in Safari on iPhone or Chrome on Android, load the PDF from your files, draw your signature with your finger, place it on the page, and download. The entire process takes under two minutes and is particularly useful when someone sends you a document to sign while you are away from your desk.
When a simple electronic signature is not enough
Certain documents in the UK still require a wet ink signature witnessed in person, regardless of electronic signature law:
- Deeds (including property transfers and lasting power of attorney)
- Wills
- Documents under seal
- Statutory declarations
For standard commercial and employment contracts, NDAs, and service agreements, a simple electronic signature is sufficient. If you are unsure about a specific document, particularly one with legal or financial consequences, confirm with a solicitor before signing electronically.
Dedicated e-signature platforms
For high-volume signing or documents that require identity verification, dedicated platforms like DocuSign, Adobe Sign, HelloSign, and Dropbox Sign offer audit trails, identity verification options, and timestamped signing records. These are appropriate for businesses that need an evidence trail and for documents where proving who signed what and when matters more than speed.
The trade-off is complexity and cost. For an individual who occasionally needs to sign a PDF and return it, a browser-based tool is both faster and less expensive than setting up and maintaining an e-signature platform subscription.
Preparing the document before signing
Before adding a signature, make sure you are working with the final version of the document. Signing and then noticing a change that needs to be made, a date, a name, a figure, means the signed document is no longer accurate and the process needs to be repeated.
If the document is very large, consider whether you need to sign every page or only specific pages. Extracting only the signature pages first, signing them, and then merging them back into the full document is one approach for long contracts where only one or two pages need your signature. This keeps the file size manageable and makes it easy to identify and review the signed sections.
After signing: sending the document
Once you have downloaded the signed PDF, check that the signature is positioned correctly before sending. The signature is embedded in the document and will display identically in any PDF viewer on any device. If the file is large and you are sending by email, run it through PDFWhisk's compression tool, compression does not affect the signature or the document content.