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PDF Form Field Inspector

Check if a PDF is fillable and list every form field: name, type, page, value and flags. Export the names as a CSV header for batch filling. Everything runs in your browser.

What Makes a PDF Fillable?

A PDF is fillable when the file itself contains form fields. In the standard form model, AcroForm, every field is a small record inside the document: a name, a type, a rectangle on a page, and a value. A viewer that finds these records draws a box, lets you click into it, and stores what you type inside the field, so the values travel with the file when you save it.

You will meet three kinds of PDF. AcroForm files carry regular fields and open in every mainstream viewer, from Acrobat to Chrome to macOS Preview. XFA files (XML Forms Architecture) were built with Adobe LiveCycle Designer and store the form as XML; the format was deprecated in the PDF 2.0 standard, and viewers that do not support it show a placeholder page instead of the form. Flat files have no fields at all: scans, photos of paper forms, print-to-PDF output, and documents exported from Word or Google Docs without form controls. The lines and boxes you see are just drawings.

Desktop viewers give the same answer, with a little guesswork. In Adobe Acrobat Reader an interactive form shows a purple message bar and the pointer turns into an I-beam over a field, while a flat form can only be marked up with the Fill & Sign tools, which place text anywhere on the page. In Preview on a Mac, an AutoFill Form button appears above a PDF whose fields it recognizes; if Preview will not let you type into the form, it offers a text box from the Form Filling Toolbar instead. This inspector reads the field records directly, so you get the answer and the full list in one step.

A scan is never fillable because a scanner produces one picture per page: there is no text layer and nothing for a viewer to click into. Print-to-PDF does the same to a form that used to be fillable, since the printer driver draws the field appearances as page graphics and drops the form dictionary. Both need fields added back before anyone can type into them, which is what Convert PDF to Fillable Form does.

How to Check If a PDF Is Fillable

  1. 1

    Drop in your PDF

    Drag the file onto the box above or click to browse. It is read locally by pdf.js and pdf-lib and never uploaded.

  2. 2

    Read the verdict

    Green means AcroForm fields were found. Amber means the file is an XFA form. Gray means it is flat and needs fields before anyone can type into it.

  3. 3

    Use the field list

    Copy the names, download the full table as CSV, or download the one-row CSV template to use as the spreadsheet header for a batch fill.

PDF Form Field Types Explained

Text (Tx)
A box you type into. It can be single-line, multiline, or a comb field that spaces characters into cells, one per box, as on tax and banking forms. Authors can add a maximum length and number or date formatting.
Checkbox (Btn)
A square that toggles between an export value, usually Yes or 1, and Off. Several checkboxes can share one name and different export values to behave as a mutually exclusive group.
Radio group (Btn, radio flag)
One field name with several round buttons, each carrying its own export value. Picking one clears the others, and the field's value becomes the export value of the chosen button.
Dropdown (Ch, combo flag)
A closed list that shows one choice at a time. Some dropdowns also accept typed text that is not in the list.
List box (Ch)
A list with its options always visible. It may allow selecting more than one value, in which case the value is a list.
Signature (Sig)
A slot for a certificate-based digital signature. You cannot type a name into it; a signing tool fills it and can lock the rest of the form.
Button (Btn, push flag)
Submit, reset, print or script triggers. A button holds no data and never appears in a spreadsheet template.

Why Field Names Matter

Every automated way of filling a PDF addresses fields by name. In a mail merge or batch fill, each column of your spreadsheet maps to one field name and each row becomes one filled PDF. Command-line tools and libraries such as pdftk, pypdf and pdf-lib take the same names, and Zapier or Make style integrations list them as the inputs you connect. A wrong or misspelled name means an empty box, not an error message.

Names are hierarchical. A name like applicant.address.city means a parent field applicant with children, and the fully qualified name joined with dots is what tools expect. This inspector always shows the full name, exactly as pdf.js and pdf-lib resolve it.

Because everything keys off the name, renaming a field silently breaks every template, script and column mapping that used the old one. If you must rename, do it once, before the form goes into circulation, and export a fresh header row for anyone who merges into it.

Common Problems With PDF Form Fields

Duplicate names share one value
Two widgets with the same fully qualified name are the same field: typing into one fills both. That is useful for "print your name on every page" and a bug when two different questions were given the same name. The Widgets count in the table exposes it.
Hidden fields
A field can be flagged Hidden or NoView by the author or by a script. It still holds data and still shows up in exports, so a merge can write into a box nobody sees. Hidden fields are flagged in the Flags column.
Fields with no widget on any page
The form tree can contain fields that were never placed on a page, often left behind by deleted widgets. They show here with page "—". Viewers cannot fill them, but scripts and merges will still see the names.
Fields on the wrong page or off the page
A widget can sit on an unexpected page or have a rectangle outside the page box. Check the Page column, and the rect coordinates in the JSON export, when a value refuses to appear where you expect it.
AcroForm dictionary but no fields
Some files carry an empty form dictionary. The fields were flattened or removed, so the PDF is treated as not fillable and needs fields again.
XFA-only forms
Dynamic XFA forms, common among older government, insurance and banking documents built in LiveCycle Designer, show only a "Please wait…" page in most viewers and have no AcroForm fields to map to. The workaround is to open the form in Adobe Acrobat Reader, print it to PDF to get a flat document, and then add regular fields to that copy.

Now fill it

JustFill fills fillable PDFs by field name and detects the boxes on flat ones. Type into a single form, or hand it a spreadsheet and get one finished PDF per row.

Frequently Asked Questions

Need to add or rename fields? Make PDF Fillable edits fields in your browser.