A fillable PDF form is a small machine: named boxes waiting for answers, checkboxes that hold a tick, dropdowns with fixed choices. Filling one properly means putting your answers into those fields — not printing the page, writing by hand and scanning it back into a fuzzy picture. This tool reads the real fields out of your form, lets you type into them here, and saves a completed copy whose answers are genuine field values, on your device.
What “fillable” really means
Forms come in two kinds that look identical on screen. A true form carries an AcroForm layer: each box is a named field (the PDF stores something like full_name, a text field, at these coordinates), and readers like Acrobat, Preview and browser PDF views let you click and type into it. A flat form is only a drawing of a form — lines and labels baked into the page with nothing to type into. This tool inspects your file's field list with pdf-lib (an open-source library running locally in your browser) and shows you exactly what it finds: every text field, checkbox, dropdown and radio group, labelled by its field name. If the list comes back empty, the page says so plainly and points you to Edit PDF, which writes over flat forms instead.
Filling, faithfully
Your answers are written into the fields with the same structures the form's own author used: text into text fields (including multiline ones), ticks into checkboxes, selections into dropdowns and radio groups. Field appearances are regenerated before saving, so the values display correctly in any reader — a filled field that only shows its answer when clicked is a classic half-done job, and it does not happen here. The saved file remains a real form: send it on, and the recipient sees your answers in the boxes and can still adjust fields you left live. Existing answers already in the form are shown pre-filled, so re-editing a half-completed form works too.
Keep it fillable, or flatten it?
The choice at the bottom decides the saved file's future. Keep the form fillable (the default) when the form still has somewhere to go — a second person completing their section, an office checking and correcting. Flatten when your answers are final: flattening bakes the field values into the page content and removes the fields, so the completed form can no longer be casually edited — the same job Flatten PDF does to any form, offered here as a finishing step. Neither route touches your original file.
Private by design
Like every CalcViso file tool, this one runs entirely in your browser. The file you choose is read by this page, processed on your device, and offered back as a download — it is never uploaded to a server, never stored, and never seen by anyone else. Close the tab and it is gone from memory.
Worked example
Press the sample button: the tool builds a small two-page form in your browser — name and email boxes, a newsletter checkbox, a favourite-colour dropdown, A4/Letter radio buttons, and a notes box on page 2 — and lists all six fields here. Fill in a name, tick the box, pick Green and A4, then save and open filled-form.pdf in any reader: every answer sits in its proper field. Save again with Flatten chosen and reopen it: the answers are still visible, but the fields are gone — the form is finished.
How to use this tool
- Drop your PDF form onto the box (or create the sample form).
- Read the field list the tool found — if it reports no fields, your file is a flat form; use Edit PDF instead.
- Type your answers, tick the boxes and make the dropdown and radio choices.
- Decide the finish: keep the form fillable, or flatten it to bake the answers in.
- Press Save filled form, download the copy, and open it in your usual PDF reader to confirm the answers sit in their fields.
Field names are the form author's labels
The label above each box here is the field's internal name with underscores turned into spaces — full_name shows as “full name”. Well-made forms name fields after what they hold; hastily made ones occasionally carry names like “Text1” or “undefined_2”, in which case the order on this page — which follows the form's own field order, usually reading order — plus the sample of any pre-filled value are your clues to which box is which. When in doubt, fill one field, save, and open the copy: the answer's position on the page identifies the field beyond argument, and your original is untouched throughout.