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PDF/PDF Form Filler

PDF Form Filler

Fill interactive PDF form fields — text, checkboxes, dropdowns — 100% browser-based

100% LOCALText fieldsCheckboxesDropdowns100% local
Saved Fills· Auto-save on
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The CalculatorPage 1
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Drop a PDF file here or click to upload
Works with PDFs that have interactive AcroForm fields. All processing happens in your browser.
Data Source & Legal Disclaimer
Effective: 2026Last updated: 2026-06-23Update: Manual review
Sources: pdf-lib

Only works with PDFs that have interactive AcroForm fields. XFA forms (often used by government agencies) are not supported. Some field types may not be detected. All processing happens in your browser — your data never leaves your device.

See all data sources & update policy →
How it worksPage 2

How interactive PDF forms are filled — illustrated

Interactive PDF forms come in two flavors. AcroForm is the classic model: the document catalog points to an /AcroForm dictionary whose /Fields array lists every field, and each field is a dictionary holding a /T (name), an /FT (type), and a /V (value). Filling a form simply sets /V and regenerates the widget's visual appearance. XFA is the newer XML-based alternative where values live inside an XML stream; pdf-lib cannot write it, which is why this tool fills AcroForm forms only.

Catalog → /AcroForm → field dictionary /V → page widget
Document catalog/Root└ /AcroFormthe page treepoints here/AcroForm/Fields [0 1 2]0 · Name1 · Email2 · Country/XFA → XML (skipped)Field dict/T (Email)/FT /Tx/V (…)value injectedby fillPage widgetjane@…/Rect on thepage rendersthe valueAcroForm vs XFAAcroForm — each field stores its value in a /V entry; filling writes it and redraws the widgetXFA — values live in an XML stream attached to /XFA; pdf-lib cannot write it, so it is skippedThis tool therefore fills AcroForm-only forms, which covers most business PDFs.

A field's value is stored once, in its /V entry, and shared by every widget on every page that references it. XFA forms keep values in an XML stream instead, so they fall outside this tool's scope.

Filling a W-9-style vendor form

A US vendor form has five AcroForm fields: name, tax ID, address, a checkbox, and a country dropdown. You want them typed in once and saved.

  1. Enumerate the fields:pdf-lib reads /AcroForm /Fields and lists “Name”, “TaxID”, “Address”, “Agree” (checkbox), and “Country” (dropdown)
  2. Type into the UI:Each field is rendered as a matching input; your values are held in local state
  3. Inject values:Fill sets /V on each field — setText for text, check/uncheck for the checkbox, select for the dropdown
  4. Refresh appearances & save:updateFieldAppearances() redraws each widget so the typed text shows, then the PDF is re-saved for download
FAQ & detailsPage 3

Fill interactive PDF forms without printing, all in-browser. Everything runs locally; nothing is uploaded.

FreeToolHub PDF Form Filler is a free browser-based tool — fill interactive PDF forms without printing, all in-browser. No signup, no upload; everything runs locally in your browser.

About this tool

What is this tool?

Fill interactive PDF forms without printing, all in-browser. Free, no signup.

Text fieldsCheckboxesDropdowns100% local

What Is PDF Form Filler?

PDF Form Filler is a free browser tool that detects and fills interactive form fields (AcroForm and XFA) in any PDF. It renders text fields, checkboxes, radio buttons, and dropdown menus as native HTML inputs overlaid on the document — no Adobe Acrobat or paid software required. The tool parses the form structure locally using pdf-lib, so your data never leaves your device. Once filled, you download the completed PDF with all field values embedded. The output is a standard filled PDF that any recipient can open and read without special software.

Who Should Use PDF Form Filler?

This tool is for anyone who receives government, legal, or corporate forms as fillable PDFs: taxpayers completing state tax forms, immigrants filling USCIS applications, tenants completing rental applications, employees onboarding with HR paperwork, patients filling medical intake forms, and contractors submitting permit applications. It is especially useful on Chromebooks and Linux machines where Adobe Acrobat is unavailable. Small business owners use it to fill vendor registration forms and W-9s. Because processing is local, it handles sensitive forms — Social Security numbers, financial data — without cloud exposure.

How to Use PDF Form Filler

Upload a fillable PDF by clicking "Choose File" or dragging it onto the drop zone. The tool scans the document for interactive fields and highlights them in blue. Click any field to type your answer, check boxes, or select from dropdowns. Tab between fields for fast data entry. When all fields are complete, click "Download Filled PDF" to save the document with your answers embedded. If the PDF has no interactive fields (flat/scanned), the tool will report zero fields detected — in that case, use PDF Annotator to add text manually over the form.

Frequently Asked Questions

Why does my PDF have no fillable fields?

Two common causes: the PDF is a scan (a picture of a form — no fields exist to fill, and you would need OCR or annotation tools instead), or it uses XFA forms, an Adobe-proprietary format that browser PDF engines including pdf.js cannot read. Standard AcroForm fields — the ones this filler reads — display text boxes automatically. If fields are missing, check whether the original was a scan before assuming the tool failed.

What does flattening a filled PDF do?

It bakes your answers into the page: the field widgets disappear and the text becomes part of the document content, like it was printed and rescanned. Flattened forms cannot be accidentally edited, sorted, or re-filled — which is what you want before emailing a completed tax form, application, or contract. Keep the unflattened original if you might need to correct an entry later; flatten only the copy you send.

Is it safe to fill forms with personal data here?

The filling runs entirely in your browser with pdf.js — the PDF and everything you type into it never leave your machine, so tax IDs, salaries, and medical details on government forms stay local. This is the decisive privacy property for form filling specifically, since the forms people need to complete are precisely the ones carrying the most sensitive data. No account, no upload, no server-side copy at any step.

Can I fill a form that is locked or has permissions set?

If the PDF has an open password you will need to enter it to open the file at all. Permission flags (no-edit, no-fill) are a different mechanism: they are honored by well-behaved software but are not encryption, and filling tools vary in whether they respect them. The honest rule: you can fill what you are authorized to fill — your own tax form, your company's application — and you should not be stripping restrictions from documents you do not have rights to modify.

Can I fill interactive PDF forms without Adobe Acrobat?

Yes. This tool detects AcroForm text fields, checkboxes, radio buttons, and dropdown menus in interactive PDFs and lets you complete them directly in your browser. A typical W-9 or lease application form takes under 2 minutes to fill, with no software installation required.

What form field types does it support?

It supports all standard AcroForm field types: text inputs, multi-line text areas, checkboxes, radio button groups, dropdown lists, and date fields. Filled values are embedded into the PDF so they display correctly when opened in any reader, and the file stays on your device throughout.

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