Two things called a signature
Someone sends a contract and asks you to sign and return it. You could draw your name with a trackpad and place the image on the page, or you could apply a cryptographic digital signature. Both are commonly called signing a PDF and they are not remotely the same operation. One is a picture of a signature; the other is a mathematical statement about the file. Knowing which one a situation needs saves both unnecessary effort and unpleasant surprises.
The difference that matters
| Drawn / image signature | Digital signature | |
|---|---|---|
| What it is | An image placed on the page | A cryptographic signature over the file's bytes, using a certificate |
| Proves who signed | No — anyone can paste any image | Yes, to the extent the certificate is trusted |
| Detects later changes | No | Yes — any edit invalidates it visibly |
| Needs a certificate | No | Yes, from a certificate authority or a signing service |
| Typical use | Everyday business documents, delivery notes, internal forms | Regulated filings, property, high-value contracts |
| What a viewer shows | Just the picture | A banner stating the signature is valid, and by whom |
A drawn signature is evidence in the ordinary sense: it shows intent, and combined with the email trail around it, that is usually enough. A digital signature is evidence in a stronger sense: it also establishes that the document has not changed since signing.
Is a drawn signature legally valid?
In most jurisdictions, for most contracts, yes. Broad electronic signature laws — the ESIGN Act and UETA in the United States, eIDAS in the European Union, and equivalents elsewhere — generally say a contract cannot be denied effect merely because it was signed electronically. What they require is that the signer intended to sign and that the signature can be associated with them.
The important caveats are real, though. Certain document types are commonly excluded or need a higher standard: wills, some property transfers, court filings, certain family law documents, and anything a regulator specifies. Some jurisdictions recognise tiers — eIDAS distinguishes a simple electronic signature from an advanced one and a qualified one, and only the qualified tier carries the same legal weight as a handwritten signature automatically. If a document matters, check what the other side and the relevant law actually require rather than assuming a drawn signature suffices. This is general information, not legal advice.
Making a drawn signature that works
Most signed PDFs look bad for avoidable reasons. A few things fix that:
- Sign on paper and photograph it if you want it to look like your real signature. A trackpad signature looks like a trackpad signature.
- Remove the background. A photographed signature on a white rectangle sitting over a ruled line is the tell-tale sign of a rushed job. A transparent PNG sits properly on the page.
- Size it to the line, not to the page. An oversized signature reads as careless.
- Date it in the field provided rather than writing over the form.
- Flatten afterwards. Until it is flattened, the signature is an annotation the recipient can drag off the page or delete. Flatten PDF paints it into the page permanently.
Sign PDF places the signature, and if the document is a form, fill the fields with Fill PDF Form first — flattening a form and then trying to complete it is a wasted round trip.
Order of operations
Getting this sequence wrong is the most common practical mistake, because several of these steps invalidate or erase each other:
- 1. Fill in every field while the form is still a form.
- 2. Place the signature and date.
- 3. Flatten, so nothing can be moved or lost in transit.
- 4. Apply a digital signature, if one is required. It must come last, because it covers the final bytes of the file — flattening or editing afterwards breaks it.
- 5. Protect, only if the recipient expects a password. Encrypting a document the recipient cannot open is a common own goal.
A note on keeping signatures safe
An image of your signature is reusable by anyone who receives it. That is a modest risk for most documents and a real one for some. Practical mitigations: do not post signed documents publicly, keep the signature image file somewhere sensible rather than a shared drive, and prefer a digital signature when a document's value would justify someone lifting the image. It is also worth noting that a signature rendered on screen is trivially extractable from a flattened PDF — flattening protects the document, not the signature image.