Create a fillable PDF form: tips and tools

Create a fillable PDF form: how does it work?

2 min read·25 July 2026

Forms you send by email need to be fillable. Learn how to make a PDF form fillable without expensive software.

Types of PDF forms

There are two types of PDF forms. Type 1: a PDF with existing form fields (AcroForm or XFA). These fields can be filled with the Fill Form tool on PDFrust. Type 2: a static PDF (e.g. a scanned form) without form fields. For this type you need to add form fields, which requires Adobe Acrobat Pro or free alternatives like LibreOffice.

Fill an existing form

Upload your form PDF to the Fill Form tool on PDFrust. All fillable fields are automatically recognized. Click each field and type your data. Click checkboxes to check them. Sign digitally with the Sign tool. Download the completed form as a new PDF.

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Flatten the form after filling

After filling, form fields still contain editable data. If you want to lock the form so nobody can change the answers, use the Flatten tool. This converts all fields to static text. Ideal for final versions you archive or submit.

Convert a static PDF to a form

Do you have a PDF without form fields? Then you need to add them manually. Free options: LibreOffice Draw (open the PDF, add text boxes), PDF24 Creator (Windows, free) or Smallpdf.com (online, limited free use). For professional results Adobe Acrobat Pro is the standard.

Protect the form with a password

Sending the form to many people and want to prevent structural edits? Lock the form with a password via the Protect tool on PDFrust. You can allow filling while blocking editing. This protects the form design while recipients can still fill it in.