How to fill a PDF form in your browser (auto-fill, free-form, and templates)

Fill any PDF form directly in your browser — AttachKit detects the form's fields, fills them by hand or from your saved profile, and the document never leaves your browser.

Before you start

• Works with any PDF. If the file has fillable fields (AcroForm — most government forms do), AttachKit detects them automatically. If it doesn't, you can still place text and date boxes anywhere on the page.
• Auto-fill pulls from your saved profile — it doesn't invent data. Save your name, address, and details once in your profile and every form fills from them.
• Many official PDFs (most USCIS forms like I-130, I-485, N-400) ship permissions-encrypted. AttachKit unlocks these on your device automatically when you drop them — nothing is uploaded.
• No PDF handy? Click Try with a sample form on the empty screen to load a sample rental application with 28 detected fields.

Steps

1. Open Fill and drop your PDF into the drop zone (or click it to browse).
2. AttachKit parses the form. The header shows how many fillable fields it found — for example "28 fillable fields detected."
3. Click Auto-fill from profile. AttachKit first matches fields to your profile entirely on-device (free, instant, no AI quota used), then sends only the leftover field names plus your saved profile details — never the PDF itself — to AI for the rest. Tax IDs like SSN and EIN are always matched on-device and never sent. A note tells you exactly what happened, e.g. "Filled 12 of 28 fields (8 from your saved profile, 4 via AI). Review and edit before downloading."
4. Fill or correct the rest by hand in the field panel beside the preview. Click any box on the PDF to jump to its input, and use the small "?" icon next to a field label for a plain-language explanation of what the field means.
5. Pick a font — Sans (Helvetica), Serif (Times Roman), or Mono (Courier). It applies to both the live preview and the downloaded PDF.
6. Optional: check Flatten (lock fields) to bake your values into the page and remove the editable fields. The result is a locked, tamper-resistant final PDF. Flattening can't be undone, so it's off by default.
7. Click Apply and download. Your file downloads with a -filled suffix, e.g. w-9-filled.pdf.

If your PDF has no form fields

Scanned, printed, or Word-exported "forms" usually have no real fields. Fill switches to free-form mode: pick Text or Date, click anywhere on the page to drop a box, type into it, and drag it into place. Or click Build fields to draw real fillable field rectangles onto the PDF — when you save and exit the builder, the new fields show up in the field panel and work like any other form.

Options worth knowing

Result

You get a filled copy of your form, ready to submit or print. After download, a "Filled PDF downloaded" card offers Sign this PDF → — it opens the filled file straight in Sign in-memory, with no re-upload, and it still never leaves your browser.

Privacy note: the PDF is processed entirely in your browser. The only things that can leave it are the optional AI requests — auto-fill (unmatched field names plus a snippet of your saved profile) and the "?" field help (just that field's name) — and the badge next to the file name tells you whenever that happens. If you've enabled Counsel Mode, auto-fill runs against your own local Ollama instead of a cloud model (the "?" field help is disabled rather than routed anywhere).

Related

• Fill troubleshooting — encrypted PDFs, missing fields, auto-fill limits
• Sign — add a signature to the filled form
• Unlock — remove a password you know before filling