# Sign a PDF digitally: 3 methods compared

> Sign a PDF on your computer or smartphone: built-in tools, scanning or an e-signature platform compared, and when each method is legally sufficient.

Source: https://smartdocs.de/en/blog/sign-pdf-digitally/

---

A PDF needs to go back signed, and it needs to happen today. There are three ways to get there: the built-in tools of Adobe and others, the classic print, sign and scan routine, and an e-signature platform. All three work, but they differ considerably in effort and, above all, in legal certainty. Here is the honest comparison.

## Method 1: Print, sign, scan

The familiar three steps: print the PDF, sign it with a pen, scan it or take a photo of it, email it back.

**Pros:** Everyone knows it, and nobody has to learn anything new.

**Cons:** It is slow, requires a printer and a scanner, and the result is worse than its reputation. What you end up with is just a picture of a signature in an image file. It can be copied into other documents at will, the document is not protected against later changes, and in a dispute the scan proves little. On top of that, there is the loss of quality: a searchable PDF turns into a pixelated photo.

**Suitable for:** Situations in which the other party expressly insists on this route. Otherwise, practically never.

## Method 2: Signing with built-in PDF tools

Adobe Acrobat Reader, the Preview app on the Mac and many PDF programs can stamp a drawn or saved signature into the document. That is faster than the scanner route and keeps the PDF clean.

**Pros:** Free, fast, no switching between paper and screen.

**Cons:** Legally, the result is hardly better than the scan: a signature image with no link to an identity, no integrity protection and no documentation of the process. Who signed when? Was the document changed afterward? The PDF says nothing about it. That may be enough for internal purposes, but for real contracts it gets thin.

**Suitable for:** Uncritical one-off cases, such as an informal confirmation letter.

## Method 3: E-signature platform

With a signature platform like SmartDocs, you upload the PDF, place the signature field and send a signing link. The other party signs in the browser, on a computer or smartphone, with no account and no app. Afterward, everyone involved receives the finished document.

**Pros:** The decisive difference lies under the hood. The platform documents the entire signature request: when the document was sent, opened and signed, from which IP address and on which device. At SmartDocs, these events are cryptographically chained, so subsequent manipulation is ruled out, and a completion certificate brings together all the evidence. In addition, all three [eIDAS signature levels](/en/signature-levels/) are available: from the simple signature to the qualified signature for documents subject to the statutory written form.

**Cons:** For regular use beyond the free allowance, the platform costs money; at SmartDocs, from €25 per seat per month in the [Pro plan](/en/pricing/).

**Suitable for:** Contracts and any document where provability matters. In other words, almost everything that gets signed in business.

## Step by step: have a PDF signed with SmartDocs

1. **Create an account:** The Free plan includes five signature requests per month, free forever and without payment details.
2. **Upload the PDF:** Upload the document and place fields for signature, name and date by drag and drop.
3. **Add recipients:** Enter the signers' email addresses and, for several people, the signing order as well.
4. **Choose the level:** SES for everyday use, AES with SMS code for important contracts, QES for the statutory written form.
5. **Send and track:** You see live who has opened and signed. Reminders go out automatically.
6. **Done:** Everyone receives the signed PDF, and you also get the completion certificate with the full chain of evidence.

## What about signing someone else's PDF yourself?

You do not need a printer for that either: simply upload the PDF you received to SmartDocs and sign it directly. Signing documents yourself is included without limits in every plan.

## Conclusion

If you just want to quickly put an image of your signature into a PDF, built-in tools will do. If you are concluding contracts, go through a signature platform: it takes the same time as the built-in tools, but you get a chain of evidence, integrity protection and the option of higher signature levels. You will notice the difference at the latest when it really counts.