What is a fillable PDF form?
A fillable PDF form is a PDF with interactive fields, such as text boxes, checkboxes, radio buttons, dropdowns and signature fields, that people can fill in on screen. The standard PDF form technology is called AcroForm: the fields and their answers are stored in the file, so most PDF readers can show and save them.
Also called: AcroForm, Interactive PDF form, PDF form fields
Updated October 14, 2026 · By the PDFZyro team
Fillable vs flat forms
Many PDFs only look like forms. A flat form has lines and boxes drawn on the page but no fields, often because it was scanned or exported without them, so a basic reader won't let you type into it. A fillable form has real fields: you click into a box and type, tick a checkbox or choose from a list, and the answers can be read back by software.
To fill in a flat form, use a tool that lets you type anywhere on the page, or turn it into a fillable form by adding fields.
What AcroForm fields can do
Each field has a name, a type and a value. Fields can be required, limit what's typed (for example to a date or a number), calculate totals from other fields, and be grouped so that only one radio button in a set can be chosen. Because answers are stored by field name, they can be exported to a spreadsheet or database, which makes fillable forms useful for applications, surveys and onboarding.
XFA is an older, different form technology from Adobe that many PDF readers can't display, and it is deprecated in PDF 2.0. If a form says you need a specific reader to open it, it's probably an XFA form.
Finishing a form
When a form is complete, you can keep the fields editable, so the recipient can process the answers, or flatten the form so the answers become part of the page and can't be changed. If others need to fill in and sign a form, an e-signature request with fields placed for each signer also gives you a record of who signed and when.
How to fill in or create a fillable form in PDFZyro
- To fill in a form, open it with Fill and type into its fields; on a flat PDF, click the blank lines and boxes PDFZyro finds for you.
- To make a fillable form, use Prepare a form to add text, checkbox, radio, dropdown, date, signature and calculated fields, or let PDFZyro detect them.
- Save. The filled or prepared form is a new version, so your blank original stays as it is.
Tools and guides
- Guide: How to fill in a PDF formHow to fill in a PDF form: fillable, flat and scanned forms, step-by-step instructions, other free ways to do it, and what to check before you send it.
- Fill PDFFill in PDF forms, even flat ones without fields.
- Sign PDFAdd your signature, initials and the date to any PDF.
Related terms
- Flattening a PDFMerging form fields and comments into the page so they can no longer be changed.
- Electronic signature (e-signature)Any electronic sign that shows a person agrees to a document, from a typed name to a drawn signature.
- OCR (optical character recognition)Software that reads the text in scans and photos so it can be searched and copied.