How to fill in a PDF form
- Add your PDF. Drag it onto the box or click to browse. The tool reads it on your device and looks for form fields.
- Check the field count. If the file has fillable fields, they appear below as labeled text boxes, checkboxes, radio buttons or dropdowns, each one matching the exact field built into the PDF.
- Type your answers. Fill in each control the same way you would in Adobe Reader or any PDF viewer with form support.
- Decide on flattening. Leave "Flatten form" checked to bake your answers into the page permanently, the usual choice for a document you are about to submit or print. Uncheck it if you want to save your progress and keep editing later.
- Apply and download. Press Apply & download and a new PDF with your answers downloads instantly.
What is a PDF form field, and when do you need this?
Many official PDFs, tax forms, job applications, rental agreements, government paperwork, are not just flat pages of text. They contain a hidden layer called an AcroForm, a set of real, structured fields the PDF's author placed on the page: a text box for your name, a checkbox for "I agree," a dropdown for your state, radio buttons for a yes/no answer. A PDF reader recognizes these fields and lets you click into them and type, the same way a web form works. This tool reads that same AcroForm data directly, so what you see on screen is the actual field the form was built with, not a generic overlay guessed from where text happens to sit on the page.
That distinction matters because it decides which tool you actually need. If a PDF has real form fields, this tool fills them in properly, keeping checkboxes as checkboxes and dropdowns as dropdowns, and can flatten the result into a document that looks identical in any viewer. If a PDF has no form fields at all, most commonly a scanned document or a form that was flattened by someone else, there is nothing here to detect, and what you actually want is Sign PDF, which lets you draw a signature and drop it anywhere on the page regardless of whether the file has any underlying form structure.
How it works
Everything runs on pdf-lib, a PDF library loaded straight into your browser tab. When you add a file, it calls the PDF's own getForm() and getFields() functions to list every field and its type, then builds a matching HTML control for each one. When you press Apply & download, your typed values are written back into those same fields using the field's own setter, a text field getssetText(), a checkbox gets check() or uncheck(), and radio buttons or dropdowns get select(), then the finished PDF is rebuilt and handed straight to your browser's download. None of this requires a server, so your document, and whatever personal details you put into it, never leaves your device.
Frequently asked questions
Does this work on a scanned PDF?
No. A scanned PDF is a flat image with no underlying form fields, so there is nothing for this tool to detect. Use Sign PDF to drop a hand-drawn signature onto a scanned document instead.
Is my PDF or my data uploaded anywhere?
No. The file is read and filled in entirely inside your browser using JavaScript. It never leaves your device or touches a server.
What does "Flatten form" actually do?
It converts your typed answers into permanent page content and removes the underlying form fields, so the PDF can no longer be edited. Leave it unchecked if you want to keep the file fillable.
What if the PDF has no fillable fields?
The tool tells you right away instead of showing a blank form. That PDF has no AcroForm data to fill in, so Sign PDF is usually the better tool for adding a signature by hand.
Related: sign a PDF · watermark a PDF · merge PDFs into one file.