Fill out PDF forms online — no Acrobat required
Auto-detect every fillable field in your PDF (text inputs, checkboxes, dropdowns, radio buttons), fill them in via a clean web form, then download the completed PDF. Optionally flatten so the values can't be edited later.
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Most government forms, tax documents, application forms, and onboarding paperwork are distributed as fillable PDFs — but the only 'official' way to fill them is with Adobe Acrobat. PDFOnly's Form Filler reads the AcroForm field definitions inside your PDF, presents them as a clean web form, and writes your answers back into the actual form fields. Optionally we can 'flatten' the result so the values become permanent (no longer editable) — useful when you're submitting and want to make sure recipients don't accidentally tweak the form they receive.
How to fill pdf form step by step
- 1
Upload a fillable PDF
Drop a PDF with form fields (AcroForm). Most government forms and 'fillable' downloads work. If the PDF is just a scanned form image without actual form fields, you'll see an empty field list — try Edit PDF or Sign PDF instead.
- 2
Fill in the auto-detected fields
We list every field by name, with the right input type (text box, checkbox, dropdown, radio group). Skip optional fields by leaving them blank.
- 3
Choose: editable or flattened
Editable = the output is a still-fillable PDF, recipients can change your answers. Flattened (default) = your answers are baked into the page, no longer editable. Choose flatten when submitting to be safe.
- 4
Click Fill and download
We write the values into the AcroForm dictionary using pdf-lib, optionally flatten, and return the completed PDF. Original styling and layout are preserved.
Why fill pdf form on PDFOnly
Auto-discovery, no manual mapping
Some tools require you to identify fields by name or coordinate. We parse the AcroForm dictionary and present everything automatically — including dropdowns and radio buttons with their valid options.
Real form-field writing, not text overlays
Some 'fill PDF' tools just overlay text on top of the PDF. We write into the actual form fields, so the result behaves like a properly completed form when opened in Acrobat or any other reader.
Flatten option prevents tampering
When you flatten, your filled values become permanent rasterized content. Recipients can't accidentally erase your name and replace it with their own — useful for legal, tax, and HR submissions.
No signup, no install
Acrobat is overkill if all you need to do is fill one form. Use this in your browser — even on your phone.
What people use fill pdf form for
A few common scenarios. If your workflow looks like one of these, this tool is a good fit.
Tax forms and government applications
IRS forms, immigration applications, benefits paperwork — all distributed as fillable PDFs. Fill them in your browser, flatten before submitting so the agency receives a locked-in copy.
Job applications and onboarding paperwork
HR sends a stack of fillable PDFs (W-4, I-9, direct deposit form, NDA). Fill them all in your browser instead of installing Acrobat.
Insurance and medical intake forms
Provider sends a fillable PDF intake form. Fill in your browser, flatten, send back — done in five minutes.
School and university forms
Enrollment forms, financial aid forms, transcript requests — all typically fillable PDFs. Fill them online, optionally print or submit electronically.
What you get
- Auto-detects every fillable field — text, checkbox, radio, dropdown
- Clean web UI — fill it in your browser, no Acrobat needed
- Flatten option locks the values so recipients can't edit them
- Works on any AcroForm PDF — government forms, applications, contracts
- Free, no signup, files auto-deleted in 1 hour
- Mobile-friendly — fill forms on your phone
Frequently asked questions
What's an AcroForm?
AcroForm is the original PDF form-field standard, built into the PDF spec. It defines fillable text boxes, checkboxes, radio buttons, dropdowns, and signature fields with names you can address programmatically. Most 'fillable' PDFs use AcroForm. (XFA, used by some old Adobe LiveCycle forms, is a separate standard we don't support — those are increasingly rare.)
What if my PDF doesn't have any form fields?
If the PDF is just a printed-and-scanned form (or a non-fillable design), there are no AcroForm fields to detect. Use Edit PDF (drag text overlays where you want them) or Sign PDF for a signature image. We'll show an empty field list in that case.
Can I save and resume later?
Not yet — fill it in one go. We're planning to add resume/draft saving for signed-in users in a future release.
Will it work on government forms (IRS, USCIS, etc.)?
Yes, for forms that are real fillable PDFs (most modern ones). Some older agency forms still use XFA, which we don't support — Acrobat Reader is your fallback for those. The W-4, I-9, most IRS 1040 schedules, and most state forms work fine.
What does 'flatten' actually do?
Flatten rasterizes your filled values into the page content stream and removes the form-field metadata. The result looks identical but is no longer editable in any PDF reader. Once flattened, your answers can't be changed without OCR'ing or re-typing.
Are signatures handled?
We treat signature fields like any other field — you type your name. For an actual signature image, use the Sign PDF tool, which lets you draw or upload a signature graphic and place it precisely.
Is this safe for tax forms with my SSN?
Files are auto-deleted within an hour and transmitted over HTTPS. That said, for highly sensitive PII (SSN, bank info), best practice is to use a tool you fully control end-to-end. Self-host if needed — our stack is open and easy to deploy.
Ready to fill pdf form?
Free to use for the basics. Files are auto-deleted within an hour and never used to train AI.
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