What kind of PDF can I use?

Use an existing fillable PDF with AcroForm fields — text fields, checkboxes, radio buttons, dropdowns or list boxes. The tool extracts those fields so rules can reference them by name.

A rule can show or hide a target field when a condition is true, or set a target field to the sum, average, product, minimum or maximum of selected source fields.

What conditions are supported?

Conditions include equals, does not equal, is checked, is unchecked, is filled and is empty. Value-based conditions compare against the text you enter in the rule composer.

Where does the logic run?

Rules are compiled to Acrobat JavaScript and embedded in the PDF. A JavaScript-capable reader such as Adobe Acrobat evaluates them while the form is being filled.

Will it work in every PDF viewer?

No. Some browser previews and lightweight mobile viewers ignore PDF JavaScript. Test the exported file in the reader your recipients will use before distributing it.

Can I edit a password-protected PDF?

Yes, if you know the password. Unlock the file when prompted, then the fields are extracted and you can add rules normally.

Does it flatten the form or remove fields?

No. The fields remain fillable; the tool injects scripts that control visibility and calculations. It does not flatten the document or convert fields to static text.

Is my PDF uploaded to a server?

No. Parsing, field extraction, rule compilation and PDF generation all run locally in your browser. Your file never leaves your device.

Formular-Logik-Designer: Regeln für ausfüllbare PDFs

Verknüpfen Sie PDF-Felder mit Ein-/Ausblend- und Berechnungsregeln, die zu Acrobat-JavaScript kompiliert werden. Kostenlos, privat, im Browser.

1. Add a fillable PDF

Import one AcroForm PDF. Fields are extracted locally so you can wire them together.

2. Build rules

Create when/then rules: show or hide targets, or set a field to a sum, average, product, min or max.

3. Apply and download

Rules compile to Acrobat JavaScript and are injected into the form, ready for a compatible PDF reader.

About Form Logic Designer

Make a Fillable PDF Behave Like a Small App

A plain AcroForm can collect answers, but it cannot react to them. Form Logic Designer reads the fields already inside your PDF and lets you describe behavior as simple when/then sentences: when this checkbox is checked, show that section; when these line items change, set the total to their sum. Each rule is compiled to Acrobat JavaScript and injected back into the document.

The result is still a normal PDF, but a compatible reader now evaluates your logic as people fill it in. Visibility rules re-run on every field change, while calculated fields participate in the form’s calculation order like native Acrobat calculations.

What You Can Wire Together

Rules are built from the fields detected in your file, so the composer stays grounded in the real form.

Show and Hide Rules

Reveal a follow-up question only when a checkbox is checked, a dropdown equals a value, or a field is filled.

Calculated Fields

Set a target to the sum, average, product, minimum or maximum of the source fields you choose.

Field-Aware Composer

Text fields, checkboxes, radio groups, dropdowns and lists are listed by name and type before you build rules.

AcroJS Output

On apply, rules become Acrobat JavaScript embedded in the PDF rather than a separate script you have to manage.

Built for Real Forms, Not Demos

Use it for intake forms that should only ask relevant questions, expense sheets that total themselves, order forms that reveal shipping options, or HR packets where one answer changes the rest of the page. Because the tool works from the existing field names, you keep the layout and accessibility of the original document.

The editor shows each rule as a readable sentence and a removable card, so you can review the logic before exporting. If the PDF is password-protected, unlock it first; if it has no AcroForm fields, the tool tells you instead of producing a silent no-op.

How It Compares

Many PDF tools can fill or flatten a form. This one changes how the form behaves while it is being filled.

Funktion	Basic PDF fillers	Desktop Acrobat scripting
Uses existing AcroForm fields
Visual when/then rule builder
Show/hide logic without writing JavaScript
Sum, average, product, min and max calculations		Manual scripting
Runs locally in the browser	Varies
No Acrobat license required

Private by Default, With Clear Limits

Forms often contain exactly the kind of personal, payroll, medical or client data that should not be uploaded to a random service. Field extraction, rule editing and PDF writing all happen in your browser; the file is not sent to a server and closing the tab discards it.

The logic you add depends on the viewer: Adobe Acrobat and other JavaScript-capable readers evaluate AcroJS, while some lightweight mobile viewers and browser preview panes ignore form scripts. Signed or certified PDFs may reject changes, and XFA forms are different from AcroForms. Test the exported file in the reader your audience actually uses.