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PDF Form Filler

Detect the fillable fields in a PDF form, fill text boxes, checkboxes, radio buttons, dropdowns and lists from a simple list, optionally flatten the answers, and download the completed form.

Overview

Fills in interactive PDF forms from a simple list of fields. It detects text boxes, checkboxes, radio buttons, dropdowns and list boxes, shows each with its name, type, page and whether it is required or read-only, and saves your answers into a new PDF. You can also flatten the form so answers become fixed page content. The form is filled in your browser, not on a server.

How It Works

Drop a fillable PDF and its fields are listed with the current values already filled in. Type into text fields, tick checkboxes and choose options from dropdowns, radio groups and lists; a filter box appears for long forms and a counter shows how many fields you changed. Tick Flatten the form if the recipient should not be able to edit the answers. Download filled PDF saves a copy, and any value that could not be written is listed.

Step-by-Step Usage Guide

  1. Drop the fillable PDF form.
  2. Fill in the fields in the list, using the filter for long forms.
  3. Decide whether to flatten the form.
  4. Click Download filled PDF and review any warnings.

Technical Specifications & Standards

Interactive PDF forms use AcroForm fields, which pdf-lib reads and writes directly. Each field keeps its own rules: maximum lengths are enforced, read-only fields are shown but not changed, and multi-line boxes get a larger input. After values are set, the field appearances are regenerated with Helvetica so every viewer displays the new answers, including viewers that do not draw forms themselves. Flattening then draws those appearances onto the page and removes the interactive fields. Helvetica in its standard encoding covers Latin characters, so characters outside that set are skipped with a warning rather than breaking the save. Some government and corporate forms are built with XFA, an older Adobe format; the tool detects it and warns you, because only the AcroForm part can be filled here. Signature fields are not filled, and a PDF without fields needs Sign PDF instead.

Targeted Use Cases

  • Completing a tax, visa or benefits form that arrived as a fillable PDF.
  • Filling an employee onboarding packet without installing a PDF editor.
  • Flattening a completed application so answers cannot be changed after sending.
  • Reviewing which fields in a form are required or read-only.

Notes & Gotchas

  • Keep an unflattened copy in case you need to correct an answer later.
  • Check required fields, marked in red, before sending the form.
  • Open the result in the recipient's usual viewer when the form contains XFA.

Frequently Asked Questions

How do I fill out a PDF form online for free?

Drop the PDF, type your answers into the listed fields, and click Download filled PDF. The form never leaves your computer and no account is needed.

What does flattening a form do?

It turns the answers into ordinary page content and removes the interactive fields, so the values can no longer be edited and look the same in every viewer.

Why does the tool say no fillable fields were found?

The PDF has no AcroForm fields; it may be a scan or a print-only form. Use Sign PDF to place text and a signature anywhere on its pages instead.

Can I type accented or non-Latin characters?

Accented Latin letters such as é and ü work. Characters outside the standard PDF font, such as Chinese or emoji, are skipped and listed as a warning after saving.

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