pdf tool

Fill a PDF form online

Open a fillable PDF and every field appears in a side panel: type into text fields, tick checkboxes and choose radio and dropdown options, with the field outlined on the page as you go. Save it still fillable, or flat so the answers become part of the page.

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How it works

  1. 1

    Open the form

    Choose the PDF or drop it on the box. The panel lists every field with its type, page and a required mark, already holding any answers saved in the file.

  2. 2

    Fill the fields

    Type into text boxes, tick checkboxes and pick from radio and dropdown lists. As you move into a field, the page drawing beside or below the panel turns to its page and outlines its box.

  3. 3

    Choose how to save

    Still fillable keeps the fields, so the answers can be changed later. Flat draws the answers into the page and removes the fields, so nobody can change them.

  4. 4

    Save the filled PDF

    Press Save the filled PDF. A required field left empty is named in a note under the button, so you can fill it and save again.

Why fill a PDF form here

Most online PDF fillers upload the file to a server, fill it there and send it back, which means a tax form, a medical history or a rental application passes through someone else's computer. This tool reads the form with pdf-lib inside your browser tab, writes your answers into it there, and hands back the new file directly. The PDF and every answer you type stay on your device; nothing is uploaded and nothing is stored, ever. You can check this by opening the network panel of your browser while you fill and save.

Field types and how they are filled

Text fields take typed answers, and a field marked for several lines gets a larger box; if the form sets a character limit, such as four for a postcode, the box stops at it. Checkboxes are ticked or cleared. Radio groups and dropdowns show their options in a list with Not chosen at the top, so an answer can also be removed. Read only fields show their value but cannot be changed, and signature fields are listed but left alone. Each answer is written into the field and its appearance redrawn, so it shows in any reader, including ones that do not draw forms themselves.

Still fillable or flat

Save still fillable when the form may need corrections, or when the recipient will add their own part. Save flat when the form is finished: each answer is drawn into the page and the field removed, which locks it and makes it show correctly in viewers that hide form fields, such as some phone previews. A field that has nothing to draw stays as a field and is named in a note. Keep the fillable copy as well, since a flat form cannot be edited.

When the form should be online instead

If you send the same PDF form to many people, collecting answers online is less work than receiving filled files. The OneCraft form builder makes classic and conversational forms, and its generator can read up to 5 attachments of 10 MB each, including the PDF form you already have.

Limits worth knowing

Dynamic XFA forms are refused, because only Adobe software builds their fields, and filling the hidden AcroForm copy would leave Acrobat showing blanks. Signature fields need a drawn or certified signature, which the sign PDF tool adds after you save. The form's own scripts do not run, so automatic totals stay as they were. Encrypted PDFs cannot be rewritten. The original file on your disk is never changed; each save is a new download.

Limits

  • XFA forms and signature fields are not fillable here; use the sign PDF tool for a drawn signature.
  • Answers are drawn with the standard Helvetica font, which covers Western European letters only; an answer with other characters is named and the save waits.
  • A PDF with no form fields, or an encrypted one, cannot be filled here, and the page says which.

What it does not do

  • It does not run the form's scripts, so totals and date checks built into the PDF do not calculate.
  • It does not add fields to a flat PDF.
  • It does not upload the file or keep your answers.

Questions people ask

Can I fill a PDF form that has no fields?

Not with this tool, because there is nothing to fill: the boxes are printed on the page. The page tells you so when the file opens. To type onto a flat PDF, use the sign PDF tool, which places text, dates and a signature anywhere on the page, or rebuild the form with real fields in a PDF form editor.

Why do my answers disappear in another PDF viewer?

Some viewers, especially simple previews on phones and in email apps, draw only the page and ignore form fields, so the answers seem to vanish. This tool redraws each field's appearance to avoid that, but the safest fix is to save the form flat, which turns every answer into part of the page that any viewer shows.

Can I save my progress and finish the form later?

Yes. Save it still fillable, and the answers so far are written into the file you download. Open that file here or in any PDF reader later, and the fields come back holding what you typed. Nothing is kept in the browser, so the downloaded file is the only copy of your progress.

Why does the tool reject some characters in my answer?

Answers are drawn with Helvetica, the standard PDF font that every reader has, and it covers English and Western European letters such as é and ü but not scripts like Greek, Cyrillic, Chinese or emoji. The field holding the character is named, and the save waits until the answer is changed. Forms that embed their own fonts are still filled with Helvetica here.

Does a required field have to be filled before I can save?

No. The tool saves whatever you have entered, then names any required field that is still empty, so you can go back, fill it and save again. Required is a flag set by the form's author; whoever receives the form may reject it if those fields are blank, so it is worth clearing the list before sending.

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Built with pdf-lib (MIT), pdf.js (Apache-2.0).

Sources

Written and checked by the OneCraft team. Last checked .