pdfcosmos

Fill PDF Forms

Fill a PDF's interactive fields on the page and download the result, entirely in your browser.

Free, fast, and privacy-first.

Add the PDF form you want to fill

or drag & drop a file here

PDF onlyone fileup to 100 MB

Fill a PDF form online: free, and nothing gets uploaded

Fill out an interactive PDF form (applications, tax forms, contracts) right on the page, then download it. pdfcosmos reads the fields and writes your answers entirely in your browser, so a form full of personal details is never uploaded.

It works with real interactive fields (an AcroForm): text boxes, checkboxes, radio buttons, and dropdowns are highlighted so you can fill them in. Optionally flatten the form on the way out to lock your answers. A flat or scanned PDF has no fillable fields. For those, use Fill & Sign to type anywhere on the page instead.

  • Fill fields right on the page

    Text, checkboxes, radio buttons, and dropdowns in a real interactive PDF form.

  • Lock it when done

    Optionally flatten the fields so your filled form can't be edited.

  • Nothing is uploaded

    pdf.js reads the fields and pdf-lib writes your answers, all in your browser.

  • No fillable fields?

    Flat or scanned PDFs have none. Use Fill & Sign to type anywhere instead.

How to fill a PDF form

  1. Add your PDF form

    Click “Select PDF”, or drag a single file with interactive fields into the upload area.

  2. Fill the fields

    Type into text boxes and pick checkboxes, radio buttons, and dropdowns right on the page.

  3. Download

    Optionally flatten the fields so they can't be edited, then download your filled PDF.

Frequently asked questions

Are my PDF files uploaded to a server?
No. Your PDF is read and filled entirely in your browser. pdf.js reads the form fields and pdf-lib writes your answers, so the file never leaves your device. You can confirm it in your browser's Network tab: no file data is sent.
What kind of PDF forms can I fill?
Forms with real interactive fields (an AcroForm): text boxes, checkboxes, radio buttons, and dropdown/list menus. When you open the file, those fields are highlighted on the page so you can fill them in.
Why does my PDF say it has no fillable fields?
It's probably a flat or scanned PDF with no interactive form fields, or an XFA form (some government/LiveCycle PDFs), which isn't supported. This tool fills existing interactive fields. It doesn't add new ones to a flat page.
What does “flatten after filling” do?
It bakes your answers into the page so the fields are no longer editable, useful when you want to send a final, locked copy. Leave it off to keep the form editable.
Why is my filled text in a different font?
Filled values are rendered with a standard font (Helvetica) so they display correctly in every PDF viewer. The rest of the document is untouched.
Is Fill PDF Forms free?
Yes, it's completely free to use, with no sign-up and nothing to install.