The simplest way: use what your software already has

Most people can create a digital signature without buying anything new. If you use Microsoft Word, Google Docs, Adobe Reader, or Apple Preview, you already have the tools built in. These programs let you draw your signature on screen, type your name as a signature, or insert an image of your handwritten signature. The signature stays attached to the document and shows who signed it and when.

The catch is that these basic signatures are not legally binding in most situations. They work fine for internal documents, agreements between people who trust each other, or anything where you just need proof that a specific person opened and saw the file. They do not work for contracts, real estate, wills, or anything that might end up in court. For those, you need a certified digital signature from a company the government recognizes.

Key Takeaways

  • Built-in signatures in Word, Google Docs, and Adobe are free and take two minutes, but are not legally binding for contracts or official documents.
  • A certified digital signature requires you to prove your identity to a third-party company and costs between $50 and $300 per year, depending on how often you sign.
  • The company that issues your certified signature is called a Certificate Authority, and the government maintains a list of approved ones.
  • Once you have a certified signature, you can sign documents on your computer without printing, signing by hand, or scanning anything back in.
  • Different documents have different rules about which type of signature they accept — always check with the other party before you spend money on a certified signature.

Creating a basic signature in Microsoft Word

Open the document you want to sign. Go to the Insert tab at the top, then click Signature Line. Word will ask you to type your name, title, and email address. After you click OK, a signature line appears in the document. Double-click on it, and a box opens where you can draw your signature with your mouse or trackpad, type your initials, or upload an image of your real signature.

Once you click Sign, the signature locks into place and the document shows the date and time you signed it. You can still edit the document before you add the signature line, but after you sign it, Word will warn you if you try to make changes. This is useful because it shows the other person that the document has not been altered since you signed it.

Creating a basic signature in Google Docs

Open your document in Google Docs. Click Insert at the top, then scroll down to Drawing, then click New. A drawing box opens. In the toolbar, find the Scribble tool (it looks like a pen), and draw your signature. You can also use the text tool to type your name in a signature-style font. When you are done, click Save and Close, and your signature appears in the document as an image.

Google Docs signatures are simpler than Word signatures — they do not lock the document or show a timestamp. They work well for internal documents or when you are sending something to someone who just needs to see that you looked at it. If you need a timestamp or want to prevent edits after signing, Google Docs is not the right tool.

Creating a basic signature in Adobe Reader or Preview

If someone sends you a PDF to sign, you can add a signature without converting it to another format. In Adobe Reader, click Fill & Sign on the left side, then click Sign. You can draw your signature, type your name, or upload an image. In Apple Preview on Mac, click Tools at the top, then Annotate, then Signature. Draw or upload your signature the same way.

PDF signatures are useful because they stay attached to the PDF itself — the other person opens the file and sees your signature right there. Like Google Docs signatures, they do not create a legal record of when you signed or prevent the document from being edited afterward.

Getting a certified digital signature from a Certificate Authority

If you need a signature that holds up in court or for official documents, you need a certified digital signature issued by a Certificate Authority. The U.S. government maintains a list of approved Certificate Authorities on the National Institute of Standards and Technology (NIST) website. Common ones include DigiCert, GlobalSign, and Sectigo.

To get a certified signature, you choose a Certificate Authority, pay their fee (usually $50 to $300 per year), and prove your identity. They may ask you to upload a government ID, answer security questions, or verify your identity through a video call. Once they confirm who you are, they issue you a digital certificate — a file that lives on your computer and contains your signature and proof that the Certificate Authority verified you.

After that, you can sign documents using software like Adobe Acrobat Pro, Microsoft Office with the certificate installed, or specialized signing software. When you sign, the software uses your certificate to create a signature that includes a timestamp, proof of who signed it, and proof that the document has not been changed since you signed it.

What happens when you sign with a certified signature

When you use a certified digital signature, the software creates a mathematical code based on the document and your certificate. This code is unique to that exact document and that exact moment in time. If anyone changes even one letter in the document after you sign it, the signature becomes invalid and shows as broken or tampered with.

The person receiving the document can verify your signature by checking it against the Certificate Authority's records. They can see your name, the date and time you signed, and confirmation that the document has not been altered. This is why certified signatures are legally binding — they create a permanent, verifiable record that you signed a specific document at a specific time.

Choosing between basic and certified signatures

Use a basic signature (the kind you create in Word, Google Docs, or Adobe) for internal memos, draft agreements, or anything where you just need proof that you saw the document. They are free, take two minutes, and work on any computer.

Use a certified signature for contracts, real estate documents, loan paperwork, medical records, or anything that might be disputed later or required by law. Check with the other party first — some organizations only accept certified signatures from specific Certificate Authorities, and some do not require them at all. Asking before you buy saves you money and frustration.

Frequently Asked Questions

Can I use a basic signature on a legal contract?

It depends on the contract and who you are dealing with. Some contracts accept basic signatures if both parties agree. Others require a certified signature by law. Always ask the other party or a lawyer before you sign — a basic signature on a document that requires a certified one may not be legally binding.

What if I lose my digital certificate?

Contact your Certificate Authority when ready. They can revoke the old certificate and issue you a new one. Until you do, anyone could potentially use your certificate to sign documents in your name. Most Certificate Authorities let you read a backup copy of your certificate, which you should store in a safe place.

Do I need special software to use a certified signature?

Most modern versions of Microsoft Office, Adobe Acrobat Pro, and Google Workspace support certified signatures. Some Certificate Authorities provide their own software. Check with your Certificate Authority about what software works with their certificates before you buy.

Can someone forge my digital signature?

Forging a certified digital signature is extremely difficult because it requires your certificate file and the password that protects it. Basic signatures are easier to copy because they are just images. If you use a certified signature, keep your certificate file and password as find as you would keep a credit card number.

How long does a digital signature last?

A certified digital signature is valid as long as the certificate is valid — usually one to three years. After that, you need to renew your certificate with the Certificate Authority. The signature itself does not expire, but if someone challenges it after your certificate has expired, proving it is valid becomes harder.