Fill PDF Form

Fill PDF Form fills in the fields a PDF already contains: text boxes, check boxes, radio buttons, dropdown menus and list boxes. Choose your file, type into the boxes it found, tick the boxes, choose the options, and download a copy with the fields filled in. It is for the everyday form that arrives as an Interactive PDF — a job application, a tax or insurance form, a school permission slip, a rental application — when you do not want to print it, write on it and scan it back.

Two kinds of form exist and this tool works with one of them. A standard AcroForm stores real fields inside the file: each field has a name, a value and a rectangle on a page, and every PDF reader lets you click in it. An XFA form (built with Adobe LiveCycle) stores its layout and data in a separate XML packet instead; readers such as Acrobat and some browsers fill those, but they have no standard fields and cannot be filled here. If a file is XFA-only, the tool says so and points you to Acrobat Reader's Print → Save as PDF. Signature fields are shown but not filled, because a signature is not a value this tool can write; push buttons are ignored too.

pdf.js draws each page and the tool lays the form's own fields over it, so you fill the boxes where they actually sit, on the page and at the size they were made. Text boxes and check boxes can be typed and ticked straight on the page; radio groups, dropdowns and list boxes appear in the field list beside the preview, because a native control would be too small to use at the zoom you read at. Every value is checked before the file is saved: a field name the form does not have, a required field left blank, a choice that is not in a field's list, and text longer than the field's maximum length are all reported, naming the field, before anything changes. When it saves, pdf-lib writes the values into the fields and redraws the appearance of each field whose value you changed using the standard Helvetica font, so a filled field may use a plainer typeface than the form's original. The rest of the document is edited in place: page text, images, links and any fields you did not touch stay exactly as they were.

Tick "Flatten form after filling" if the copy is going to someone who should see your answers but not change them: each field's value is drawn onto the page as ordinary content and the fields are removed, using the same writer as Flatten PDF. That also fixes how the form looks in viewers that render fields poorly. Note what changing a file does to a digital signature: if the PDF already carries a certificate-based signature, saving a filled copy rewrites the document and that signature stops validating. The tool warns you; ask the sender for a version you may edit.

Password-protected PDFs are refused — a locked file cannot be edited here either. Files up to 200 MB and any number of pages are accepted. Nothing is uploaded: the PDF is read and written in your browser tab with pdf-lib, and you can confirm in the Network tab of your browser's developer tools that no request carries the file. The page loads its own scripts and analytics, never your document.

1. The file's signature is checked (a renamed JPG is named as a JPG), a file over 200 MB is refused before it is read, and pdf-lib opens it; an encrypted file is refused and a damaged one is reported as damaged. Any XFA layer is noted and removed, because pdf-lib cannot read or write XFA. 2. The standard form's fields are enumerated. For each field, its type is read from the field dictionary, its value from the current setting (text, tick, or the selected option or options), its choices from /Opt, and read-only and required flags from the field flags. Each widget's page is found by walking every page's /Annots, and its rectangle is read as [x0, y0, x1, y1] from /Rect. 3. pdf.js renders the page you are on and each field is overlaid at the percentage position its rectangle maps to, accounting for the page's visible area and rotation. 4. On saving, every value is validated first — unknown field name, blank required field, a choice not in the field's list, text beyond the field's maximum length — then applied. Values are checked against the WinAnsi character set (the Latin alphabet, digits and common punctuation) because pdf-lib redraws each changed field's appearance in Helvetica; a value it cannot encode is refused with a message pointing at the PDF editor. 5. The document is saved as <name>-filled.pdf. With flattening on, the filled bytes are passed to Flatten PDF's writer, which draws each field's appearance into the page and removes the form. 6. Read-only fields, signature fields and push buttons cannot be filled and are counted as skipped in the result.