--- title: "Fill PDF Form Online - Free and Private | CanDoYa" description: "Fill a PDF form online for free. Complete standard AcroForm text, checkbox, radio, and choice fields privately, then download your PDF." url: https://candoya.com/tools/fill-pdf-form/ locale: en type: browser-tool --- # Fill PDF Form Online Category: PDF ## How can I fill a PDF form online? Use this PDF form filler to open an interactive AcroForm, complete its text boxes, checkboxes, radio groups, dropdowns, and option lists, then download a new PDF. You can keep fields editable or flatten a final copy. The document is processed locally in your browser and is never uploaded. This tool fills **interactive fields already embedded in a PDF**. It reads each field's internal name and available choices, then gives you a matching browser control. Read-only controls stay disabled, while unsupported buttons and signature fields remain untouched in the output. Choose flattening when you want the entered values baked into the page for printing or submission. Leave it off if you expect to reopen the PDF and change answers later. Flattening is permanent for the downloaded copy, so keep the original template. ## How to use it 1. **Choose a fillable PDF** - Drop an AcroForm PDF onto the tool or select one from your device. The browser detects its existing fields. 2. **Complete the fields** - Enter text and use the checkboxes, radio groups, dropdowns, and option lists generated from the PDF. 3. **Choose editable or flattened output** - Leave flattening off to preserve editable fields, or turn it on to make the current appearances permanent. 4. **Create and download** - Create the filled PDF, review the result summary, and download the new file to your device. ## Who it's for - **Job applicants** completing interactive application forms without sending personal details to an upload service. - **Employees and volunteers** filling onboarding, consent, reimbursement, or registration PDFs. - **Small teams** preparing editable drafts first, then flattened submission copies when the answers are final. - **Administrators** testing field names, required controls, and choice options in a standard AcroForm template. ## Expert note AcroForm and XFA are different form technologies. pdf-lib supports standard AcroForm fields but not XFA, so this tool rejects XFA documents rather than producing a PDF that appears complete while silently losing dynamic values. Flatten only a final copy because it removes the interactive field objects from that output. ## Frequently asked questions ### Is my PDF uploaded when I fill the form? No. The PDF bytes and every value you enter stay inside your browser. pdf-lib loads as local application code when you choose a document, then the browser creates the downloadable PDF in memory. CanDoYa does not receive or store the form, answers, or output file. ### Is this PDF form filler free? Yes. You can fill and download standard AcroForm PDFs without an account, payment, watermark, or daily quota. The tool also includes a sample form so you can test the workflow before opening your own document. ### What are the PDF size and field limits? The tool accepts one PDF up to 100 MB and has no separate field-count limit. Available browser memory creates the practical limit, so very large or unusually complex forms may work better on a desktop computer than on an older phone. ### Which PDF form fields can I fill? You can fill standard AcroForm text boxes, checkboxes, radio groups, dropdowns, and option lists. Read-only fields are displayed but disabled. Buttons, unknown field types, and signature fields are preserved without being edited. ### Why does my PDF say that no fields were found? A document can look like a form without containing interactive fields. Scans, flattened forms, and PDFs made from a word processor may contain only page text and lines. This tool does not use OCR or place new text boxes, so it needs existing AcroForm controls. ### Can this tool fill an XFA PDF form? No. XFA is an Adobe-specific XML form system that pdf-lib does not support. The tool detects XFA and stops before editing. Open that file in Adobe Acrobat or another XFA-aware application so dynamic fields, calculations, and layout behavior remain intact. ### Can I fill a password-protected PDF? No. Unlock a copy in a trusted PDF application first, provided you have permission to modify it. This tool does not request, transmit, or store PDF passwords, and it does not bypass document restrictions. ### What does flattening a PDF form do? Flattening turns the current field appearances into ordinary page content and removes the interactive controls from the downloaded copy. It can improve consistency when printing or submitting a final form, but the answers can no longer be changed as form fields afterward. Existing digital signature fields are not signed by this tool. ## Related tools - [PDF Form Data Extractor](https://candoya.com/tools/extract-pdf-form-data/) - [PDF Signer](https://candoya.com/tools/sign-pdf/) - [PDF Metadata Editor](https://candoya.com/tools/edit-pdf-metadata/) - [PDF to Text](https://candoya.com/tools/pdf-to-text/) - [PDF Watermark](https://candoya.com/tools/add-watermark-to-pdf/) --- *Markdown edition of , published for AI agents and other automated readers. Index of key pages: .*