Filling in PDF forms

A form in blupdf is a printed layout with blanks: lines to write on, boxes to tick, spaces after a label. blupdf treats every form the same way, whether it came from a word processor, a government website or a scanner: the blanks become places you type, and what you type is set in the form's own font on the line where it belongs.

The Fill in tab

Open the blupdf AI panel with Ask AI and switch to the Fill in tab. blupdf lists every blank in the document, one row per blank, named by the words next to it: "Landlord", "Date", "Amount". The count of open blanks sits on the tab. Type a value in a row and it is written into the document, on that line, in that font and size. When everything is done the tab says "All blanks filled".

A blank, for this purpose, is a run of underscores in the form's text (________). Labels come from the words before the blank on its line, or after it, or from the cell to the left or the line above; a form drafted with Create with AI brings its own labels. If a form has empty boxes rather than underscore lines, the tab says "No blanks found" and you use the Text tool instead.

Typing anywhere with the Text tool

Choose Text in the toolbar and click where the answer goes: inside a box, on a line, after a label. A new block is created there with the font and size of the nearest text. Type, then click away. For boxes that take one character each, type the characters together and open Spacing in the toolbar to widen the letter spacing until they sit in their boxes. To tick a checkbox, click inside it with the Text tool and type an X.

Asking blupdf AI to fill it

In the blupdf AI tab you can hand over the whole job: "fill in the tenant as John Smith, the address as 12 Market Street and the start date as 1 October 2026". blupdf AI writes each value into the right blank, keeps the form's number style, and asks back when a value is missing instead of inventing one. Each request costs 100 credits plus 1 credit per character written; see Editing with blupdf AI.

Scanned forms

A scanned form is recognised on first open (80 credits per page) and rebuilt as a real page: its labels become text, its lines and boxes are redrawn, and its checkboxes come back as boxes with their marks. From there it fills like any other form. Underscore lines survive recognition as blanks, so the Fill in tab usually works on scans too.

Interactive form fields

blupdf does not read a PDF's interactive form fields, the kind some viewers show as blue boxes. It treats the page as a printed form: whatever you type becomes page text. The upside is that the filled copy looks the same in every viewer and nothing can be cleared by accident; the downside is that a recipient cannot edit your entries as fields.

Signing the form

Signature lines take the signature tool: draw or type your signature once, click the line, done. See Signing a PDF.

Downloading

Download as PDF and your entries are part of the page, in the form's font. The recipient sees a completed form in any viewer. DOCX gives you the form's text and your entries as a Word document; JPG and PNG give you page images.

Credits

• Recognising a scanned form page: 80 credits, once.
• Opening a digital form: 50 credits per page, once.
• Text you type: 1 credit per character.
• blupdf AI filling in values: 100 credits per request, plus the characters written.
• Signatures and downloads: free.

Tips

• Fill from the top down in the Fill in tab; it is faster than hunting for lines on the page.
• Zoom in on dense government or insurance forms so the boxes are easy to hit.
• Open the downloaded file once in a plain viewer before sending it; that is what the recipient sees.