Steps
Fill in the form fields
Open the PDF. Its text boxes, checkboxes, drop-down lists and radio buttons are listed as a web form; field names come from the PDF, so compare them with the page if a label is unclear. Leave Flatten unticked here so you can still sign and check the file. If the tool finds no fields, the form is a flat scan: skip to the next step and use Add text to type on the page. Standard form fonts cover Western European letters only.
Add your signature
Open the filled PDF, go to the page with the signature line and press Add signature. Draw with a finger, stylus or mouse, type your name in a handwriting-style font, or upload a photo of your signature. Drag it onto the line and resize it with the round handle; add the date or ticks the same way. Check every page that needs a signature or initials before you press Save PDF. Untick Remember on this device if you are on a shared computer.
Flatten, then send
Open the signed PDF and press Flatten and save. The form answers become fixed page content that cannot be edited and looks the same in every viewer; the signature was already drawn into the page in the previous step. Flattening cannot be undone, so keep the unflattened file. If the tool says there are no form fields, the file is already flat and you can use it as it is. Then attach the downloaded PDF to your email, or upload it where it was requested.
Requirements and sources
| What | Value | Source |
|---|---|---|
| US ESIGN Act - electronic signatures and records (15 U.S.C. 7001(a)(1)) | a signature, contract, or other record relating to such transaction may not be denied legal effect, validity, or enforceability solely because it is in electronic form | 15 U.S.C. 7001 - General rule of validity (United States Code, 2023 edition, govinfo) Last verified 2026-10-21 |
| US ESIGN Act - exception for wills (15 U.S.C. 7003(a)(1)) | a statute, regulation, or other rule of law governing the creation and execution of wills, codicils, or testamentary trusts; | 15 U.S.C. 7003 - Specific exceptions (United States Code, 2023 edition, govinfo) Last verified 2026-10-21 |
| EU eIDAS - legal effect of electronic signatures, including simple ones (Article 25, as summarised by the European Commission) | An electronic signature (either simple, advanced or qualified) shall not be denied legal effect and admissibility as evidence in legal proceedings solely on the grounds that it is in an electronic form or that it does not meet the requirements for qualified electronic signatures. | European Commission - eSignature FAQ (What are the legal effects of an electronic signature?) Last verified 2026-10-21 |
| EU eIDAS - qualified electronic signatures | Regarding qualified electronic signatures, they explicitly have the equivalent legal effect of handwritten signatures across all EU Member States. | European Commission - eSignature FAQ (What are the legal effects of an electronic signature?) Last verified 2026-10-21 |
| Gmail - attachment size limit when sending the signed PDF back (personal accounts) | For personal Gmail accounts, the limit is 25 MB. | Send attachments with your Gmail message - Gmail Help Last verified 2026-10-21 |
FAQ
Is a signature added this way legally valid?
In many places a simple electronic signature is accepted for everyday agreements. In the US, the ESIGN Act says a signature may not be denied legal effect solely because it is electronic, but it excludes some documents, such as wills, codicils and testamentary trusts. In the EU, the European Commission's eSignature FAQ explains that under eIDAS a simple electronic signature cannot be refused legal effect or as evidence just because it is electronic, while only a qualified electronic signature has the same effect as a handwritten one. The UK and other countries have their own rules, and some uses need a stronger type of signature. If the recipient asks for a specific type of signature, follow their instructions. This is general information, not legal advice.
Why flatten the PDF after signing?
Unflattened form fields can be changed by anyone who opens the file, and some viewers show them differently or not at all. Flattening turns the answers into ordinary page content, so the recipient sees exactly what you filled in. It removes the ability to edit, so keep your unflattened copy.
The PDF has no fillable fields. Can I still fill it in?
Yes. Skip the first step and use Add text in the sign step to type onto the page, Tick for checkboxes and Date for the date. You can then skip flattening, because typed text is drawn straight into the page.
Where is my signature stored?
Only in your browser. If Remember on this device is ticked, the signature is kept in this browser's storage so you can reuse it next time; untick it, or clear the site's data, on a shared or public computer. The PDF itself is never uploaded.
Can I sign on my phone?
Yes. Open the PDF from your phone's files, press Add signature and sign with your finger. Drag it onto the signature line, then check the saved file in your phone's PDF viewer before sending it.
General information, not legal advice; some documents (e.g. wills, certain court or real-estate papers) may need a handwritten, witnessed or qualified signature; check with the recipient or a lawyer. BufferMint is not affiliated with any e-signature provider or government body. Files are processed in your browser and are not uploaded.